diff --git a/src/si/coulomb_constant.rs b/src/si/coulomb_constant.rs
new file mode 100644
index 00000000..ea04c8f8
--- /dev/null
+++ b/src/si/coulomb_constant.rs
@@ -0,0 +1,96 @@
+//! Coulomb constant (base unit kilogram cubic meter per second to the fourth power square ampere, kg · m³ · s⁻⁴ · A⁻²).
+
+quantity! {
+    /// Coulomb constant (base unit kilogram cubic meter per second to the fourth power square ampere, kg · m³ · s⁻⁴ · A⁻²).
+    quantity: CoulombConstant; "coulomb constant";
+    /// Dimension of coulomb constant, ML³T⁻⁴I⁻² (base unit kilogram cubic meter per second to the fourth power square ampere, kg · m³ · s⁻⁴ · A⁻²).
+    dimension: ISQ<
+        P3,     // length
+        P1,     // mass
+        N4,     // time
+        N2,     // electric current
+        Z0,     // thermodynamic temperature
+        Z0,     // amount of substance
+        Z0>;    // luminous intensity
+    units {
+        @kilogram_cubic_meter_per_second_to_the_fourth_power_square_ampere: prefix!(none); "kg·m³·s⁻⁴·A⁻²",
+            "kilogram cubic meter per second to the fourth power square ampere", "kilograms cubic meter per second to the fourth power square ampere";
+        @meter_per_farad: prefix!(none); "m/F",
+            "meter per farad", "meters_per_farad";
+        @coulomb_constant: 8.987_551_792_261_172_E9 ; "kₑ", // Derived from CODATA as 1/(4πε₀)
+            "coulomb constant", "coulomb constants";
+    }
+}
+
+#[cfg(test)]
+mod test {
+    storage_types! {
+        use crate::num::One;
+        use crate::si::electric_current as i;
+        use crate::si::electric_permittivity as epsilon;
+
+        use crate::si::coulomb_constant as ke;
+        use crate::si::quantities::*;
+        use crate::si::mass as m;
+        use crate::si::time as t;
+        use crate::si::volume as v;
+        use crate::tests::Test;
+
+        #[test]
+        fn check_dimension() {
+            let _: CoulombConstant<V> = Mass::new::<m::kilogram>(V::one())
+                * Volume::new::<v::cubic_meter>(V::one())
+                / Time::new::<t::second>(V::one())
+                / Time::new::<t::second>(V::one())
+                / Time::new::<t::second>(V::one())
+                / Time::new::<t::second>(V::one())
+                / ElectricCurrent::new::<i::ampere>(V::one())
+                / ElectricCurrent::new::<i::ampere>(V::one());
+        }
+
+        #[test]
+        fn check_units() {
+            test::<m::kilogram, v::cubic_meter, t::second, i::ampere, ke::kilogram_cubic_meter_per_second_to_the_fourth_power_square_ampere>();
+
+            fn test<M: m::Conversion<V>, VOL: v::Conversion<V>, T: t::Conversion<V>, I: i::Conversion<V>, KE: ke::Conversion<V>>() {
+                Test::assert_approx_eq(&CoulombConstant::new::<KE>(V::one()),
+                    &(Mass::new::<M>(V::one())
+                    * Volume::new::<VOL>(V::one())
+                    / Time::new::<T>(V::one())
+                    / Time::new::<T>(V::one())
+                    / Time::new::<T>(V::one())
+                    / Time::new::<T>(V::one())
+                    / ElectricCurrent::new::<I>(V::one())
+                    / ElectricCurrent::new::<I>(V::one())));
+            }
+        }
+
+        #[test]
+        fn check_units_farad_meter() {
+            test::<epsilon::farad_per_meter, ke::kilogram_cubic_meter_per_second_to_the_fourth_power_square_ampere>();
+            test::<epsilon::farad_per_meter, ke::meter_per_farad>();
+
+            fn test<EPS: epsilon::Conversion<V>, KE: ke::Conversion<V>>() {
+                Test::assert_approx_eq(&CoulombConstant::new::<KE>(V::one()),
+                    &(V::one()
+                    / ElectricPermittivity::new::<EPS>(V::one())
+                   ));
+            }
+        }
+
+        #[test]
+        fn check_units_ke() {
+            test::<epsilon::vacuum_electric_permittivity, ke::coulomb_constant>();
+
+            fn test<EPS: epsilon::Conversion<V>, KE: ke::Conversion<V>>() {
+                Test::assert_approx_eq(&CoulombConstant::new::<KE>(V::one()),
+                     &(
+                    
+                    // 1 / (4 · π)
+                    7.957_747_154_594_768_E-2 * V::one() / ElectricPermittivity::new::<EPS>(V::one())
+                   ));
+            }
+        }
+
+    }
+}
diff --git a/src/si/mod.rs b/src/si/mod.rs
index 9e7d9ff0..81341984 100644
--- a/src/si/mod.rs
+++ b/src/si/mod.rs
@@ -60,6 +60,7 @@ system! {
         capacitance::Capacitance,
         catalytic_activity::CatalyticActivity,
         catalytic_activity_concentration::CatalyticActivityConcentration,
+        coulomb_constant::CoulombConstant,
         curvature::Curvature,
         diffusion_coefficient::DiffusionCoefficient,
         dynamic_viscosity::DynamicViscosity,
@@ -103,16 +104,19 @@ system! {
         mass_flux::MassFlux,
         mass_rate::MassRate,
         molar_concentration::MolarConcentration,
+        molar_electric_charge::MolarElectricCharge,
         molar_energy::MolarEnergy,
         molar_flux::MolarFlux,
         molar_heat_capacity::MolarHeatCapacity,
         molar_mass::MolarMass,
         molar_volume::MolarVolume,
         momentum::Momentum,
+        newtonian_constant_of_gravitation::NewtonianConstantOfGravitation,
         power::Power,
         pressure::Pressure,
         radiant_exposure::RadiantExposure,
         ratio::Ratio,
+        reciprocal_amount_of_substance::ReciprocalAmountOfSubstance,
         solid_angle::SolidAngle,
         specific_area::SpecificArea,
         specific_heat_capacity::SpecificHeatCapacity,
@@ -120,6 +124,7 @@ system! {
         surface_electric_current_density::SurfaceElectricCurrentDensity,
         temperature_coefficient::TemperatureCoefficient,
         temperature_gradient::TemperatureGradient,
+        stefan_boltzmann_constant::StefanBoltzmannConstant,
         temperature_interval::TemperatureInterval,
         thermal_conductivity::ThermalConductivity,
         thermodynamic_temperature::ThermodynamicTemperature,
diff --git a/src/si/molar_electric_charge.rs b/src/si/molar_electric_charge.rs
new file mode 100644
index 00000000..d718aa2a
--- /dev/null
+++ b/src/si/molar_electric_charge.rs
@@ -0,0 +1,65 @@
+//! Molar electric charge (base unit coulomb per mole, s · A · mol⁻¹).
+
+quantity! {
+    /// Molar electric charge (base unit coulomb per mole, s · A · mol⁻¹).
+    quantity: MolarElectricCharge; "molar electric charge";
+    /// Dimension of molar electric charge, TIN⁻¹ (base unit coulomb per mole, s · A · mol⁻¹).
+    dimension: ISQ<
+        Z0,     // length
+        Z0,     // mass
+        P1,     // time
+        P1,     // electric current
+        Z0,     // thermodynamic temperature
+        N1,     // amount of substance
+        Z0>;    // luminous intensity
+    units {
+        @coulomb_per_mole: prefix!(none); "C/mol",
+            "coulomb per mole", "coulombs per mole";
+        @faraday_constant: 96_485.332_123_310_03 ; "F", // CODATA value 96_485.332_12
+            "faraday constant", "faraday constants";
+
+    }
+}
+
+#[cfg(test)]
+mod test {
+    storage_types! {
+        use crate::num::One;
+
+        use crate::si::amount_of_substance as aos;
+        use crate::si::quantities::*;
+        use crate::si::electric_charge as q;
+        use crate::si::molar_electric_charge as mec;
+        use crate::si::reciprocal_amount_of_substance as raos;
+
+        use crate::tests::Test;
+
+        #[test]
+        fn check_dimension() {
+            let _: MolarElectricCharge<V> = ElectricCharge::new::<q::coulomb>(V::one())
+                / AmountOfSubstance::new::<aos::mole>(V::one());
+        }
+
+        #[test]
+        fn check_units() {
+            test::<q::coulomb, aos::mole, mec::coulomb_per_mole>();
+
+            fn test<Q: q::Conversion<V>, AOS: aos::Conversion<V>, MEC: mec::Conversion<V>>() {
+                Test::assert_approx_eq(&MolarElectricCharge::new::<MEC>(V::one()),
+                    &(ElectricCharge::new::<Q>(V::one())
+                        / AmountOfSubstance::new::<AOS>(V::one())));
+            }
+        }
+
+        #[test]
+        fn check_units_na() {
+            test::<q::elementary_charge, raos::avogadro_constant, mec::faraday_constant>();
+
+            fn test<Q: q::Conversion<V>, RAOS: raos::Conversion<V>, MEC: mec::Conversion<V>>() {
+                Test::assert_approx_eq(&MolarElectricCharge::new::<MEC>(V::one()),
+                    &(ElectricCharge::new::<Q>(V::one())
+                        * ReciprocalAmountOfSubstance::new::<RAOS>(V::one())));
+            }
+        }
+    }
+}
diff --git a/src/si/newtonian_constant_of_gravitation.rs b/src/si/newtonian_constant_of_gravitation.rs
new file mode 100644
index 00000000..0275ee47
--- /dev/null
+++ b/src/si/newtonian_constant_of_gravitation.rs
@@ -0,0 +1,59 @@
+//! Newtonian constant of gravitation (base unit cubic meter per kilogram square second, m³ · kg⁻¹ · s⁻²).
+
+quantity! {
+    /// Newtonian constant of gravitation (base unit cubic meter per kilogram square second, m³ · kg⁻¹ · s⁻²).
+    quantity: NewtonianConstantOfGravitation; "newtonian constant of gravitation";
+    /// Dimension of newtonian constant of gravitation, L³M⁻¹T⁻² (base unit cubic meter per kilogram square second, m³ · kg⁻¹ · s⁻²).
+    dimension: ISQ<
+        P3,     // length
+        N1,     // mass
+        N2,     // time
+        Z0,     // electric current
+        Z0,     // thermodynamic temperature
+        Z0,     // amount of substance
+        Z0>;    // luminous intensity
+    units {
+        @cubic_meter_pre_kilogram_square_second: prefix!(none); "m³·kg⁻¹·s⁻²",
+            "cubic meter per kilogram square second", "cubic meters per kilogram square second";
+        @newtonian_constant_of_gravitation: 6.674_30_E-11; "G",
+            "newtonian constant of gravitation", "newtonian constants of gravitation";
+    }
+}
+
+#[cfg(test)]
+mod test {
+    storage_types! {
+        use crate::num::One;
+        use crate::si::mass as m;
+        use crate::si::newtonian_constant_of_gravitation as g;
+        use crate::si::quantities::*;
+        use crate::si::time as t;
+        use crate::si::length as l;
+        use crate::tests::Test;
+
+        #[test]
+        fn check_dimension() {
+            let _: NewtonianConstantOfGravitation<V> = Length::new::<l::meter>(V::one())
+                * Length::new::<l::meter>(V::one())
+                * Length::new::<l::meter>(V::one())
+                / Mass::new::<m::kilogram>(V::one())
+                / Time::new::<t::second>(V::one())
+                / Time::new::<t::second>(V::one());
+        }
+
+        #[test]
+        fn check_units() {
+            test::<l::meter, m::kilogram, t::second, g::cubic_meter_pre_kilogram_square_second>();
+
+            fn test<L: l::Conversion<V>, M: m::Conversion<V>, T: t::Conversion<V>, G: g::Conversion<V>>() {
+                Test::assert_approx_eq(&NewtonianConstantOfGravitation::new::<G>(V::one()),
+                    &(Length::new::<L>(V::one())
+                    * Length::new::<L>(V::one())
+                    * Length::new::<L>(V::one())
+                    / Mass::new::<M>(V::one())
+                    / Time::new::<T>(V::one())
+                    / Time::new::<T>(V::one())));
+            }
+        }
+    }
+}
diff --git a/src/si/reciprocal_amount_of_substance.rs b/src/si/reciprocal_amount_of_substance.rs
new file mode 100644
index 00000000..f25d2cc5
--- /dev/null
+++ b/src/si/reciprocal_amount_of_substance.rs
@@ -0,0 +1,50 @@
+//! Reciprocal amount of substance (base unit reciprocal mole, mol⁻¹).
+
+quantity! {
+    /// Reciprocal amount of substance (base unit reciprocal mole, mol⁻¹).
+    quantity: ReciprocalAmountOfSubstance; "reciprocal amount of substance";
+    /// Dimension of reciprocal amount of substance, N⁻¹ (base unit reciprocal mole, mol⁻¹).
+    dimension: ISQ<
+        Z0,     // length
+        Z0,     // mass
+        Z0,     // time
+        Z0,     // electric current
+        Z0,     // thermodynamic temperature
+        N1,     // amount of substance
+        Z0>;    // luminous intensity
+    units {
+        @reciprocal_mole: prefix!(none); "mol⁻¹",
+            "reciprocal mole", "reciprocal moles";
+        @avogadro_constant: 6.022_140_76_E23; "Nᴀ",
+            "Avogadro constant", "Avogadro constants";
+    }
+}
+
+#[cfg(test)]
+mod test {
+    storage_types! {
+        use crate::num::One;
+        use crate::si::amount_of_substance as aos;
+        use crate::si::quantities::*;
+        use crate::si::reciprocal_amount_of_substance as raos;
+        use crate::tests::Test;
+
+        #[test]
+        fn check_dimension() {
+            let _: ReciprocalAmountOfSubstance<V> = V::one()
+                / AmountOfSubstance::new::<aos::mole>(V::one());
+        }
+
+        #[test]
+        fn check_units() {
+            test::<aos::mole, raos::reciprocal_mole>();
+            test::<aos::particle, raos::avogadro_constant>();
+
+            fn test<AOS: aos::Conversion<V>, RAOS: raos::Conversion<V>>() {
+                Test::assert_approx_eq(&ReciprocalAmountOfSubstance::new::<RAOS>(V::one()),
+                    &(V::one()
+                        / AmountOfSubstance::new::<AOS>(V::one())));
+            }
+        }
+    }
+}
diff --git a/src/si/stefan_boltzmann_constant.rs b/src/si/stefan_boltzmann_constant.rs
new file mode 100644
index 00000000..fbbb4a8f
--- /dev/null
+++ b/src/si/stefan_boltzmann_constant.rs
@@ -0,0 +1,60 @@
+//! Stefan-Boltzmann constant (base unit watt per square meter kelvin to the fourth power, kg · s⁻³ · K⁻⁴).
+
+quantity! {
+    /// Stefan-Boltzmann constant (base unit watt per square meter kelvin to the fourth power, kg · s⁻³ · K⁻⁴).
+    quantity: StefanBoltzmannConstant; "Stefan-Boltzmann constant";
+    /// Dimension of Stefan-Boltzmann constant, MT⁻³Th⁻⁴  (base unit watt per square meter kelvin to the fourth power,  kg · s⁻³ · K⁻⁴).
+    dimension: ISQ<
+        Z0,     // length
+        P1,     // mass
+        N3,     // time
+        Z0,     // electric current
+        N4,     // thermodynamic temperature
+        Z0,     // amount of substance
+        Z0>;    // luminous intensity
+    units {
+        @watt_per_square_meter_kelvin_to_the_fourth_power: prefix!(none); "W/(m²·K⁴)",
+            "watt per square meter kelvin to the fourth power", "watt per square meter kelvin to the fourth power";
+        @stefan_boltzmann_constant: 5.670_374_419_E-8; "σ",
+            "stefan-boltzmann constant", "stefan-boltzmann constants";
+    }
+}
+
+#[cfg(test)]
+mod test {
+    storage_types! {
+        use crate::num::One;
+        use crate::si::power as p;
+        use crate::si::stefan_boltzmann_constant as sigma;
+        use crate::si::quantities::*;
+        use crate::si::thermodynamic_temperature as t;
+        use crate::si::area as area;
+        use crate::tests::Test;
+
+        #[test]
+        fn check_dimension() {
+            let _: StefanBoltzmannConstant<V> = Power::new::<p::watt>(V::one())
+                / Area::new::<area::square_meter>(V::one())
+                / ThermodynamicTemperature::new::<t::kelvin>(V::one())
+                / ThermodynamicTemperature::new::<t::kelvin>(V::one())
+                / ThermodynamicTemperature::new::<t::kelvin>(V::one())
+                / ThermodynamicTemperature::new::<t::kelvin>(V::one());
+        }
+
+        #[test]
+        fn check_units() {
+            test::<p::watt, area::square_meter, t::kelvin, sigma::watt_per_square_meter_kelvin_to_the_fourth_power>();
+
+            fn test<P: p::Conversion<V>,  A: area::Conversion<V>, T: t::Conversion<V>, SIGMA: sigma::Conversion<V>>() {
+                Test::assert_approx_eq(&StefanBoltzmannConstant::new::<SIGMA>(V::one()),
+                    &(Power::new::<P>(V::one())
+                        / Area::new::<A>(V::one())
+                        / ThermodynamicTemperature::new::<T>(V::one())
+                        / ThermodynamicTemperature::new::<T>(V::one())
+                        / ThermodynamicTemperature::new::<T>(V::one())
+                        / ThermodynamicTemperature::new::<T>(V::one())
+                    ));
+            }
+        }
+    }
+}