...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::units::si::constants::codata::BOOST_UNITS_PHYSICAL_CONSTANT — CODATA recommended values of the fundamental physical constants: NIST SP 961.
BOOST_UNITS_PHYSICAL_CONSTANT(e, quantity< electric_charge >, 1.602176487e-19 * coulombs, 4.0e-27 * coulombs);