"Avogadro constant". The NIST Reference on Constants, Units, and Uncertainty. May 2019. Archived from the original on 2000-10-25. Retrieved 24 June 2021.
"Molar mass of carbon-12". The NIST Reference on Constants, Units, and Uncertainty. May 2019. Archived from the original on 2000-12-06. Retrieved 24 June 2021.
"Proton mass in u". The NIST Reference on Constants, Units, and Uncertainty. May 2019. Archived from the original on 2000-12-07. Retrieved 24 June 2021.
"neutron mass in u". The NIST Reference on Constants, Units, and Uncertainty. May 2019. Archived from the original on 2000-12-07. Retrieved 24 June 2021.
"Avogadro constant". The NIST Reference on Constants, Units, and Uncertainty. May 2019. Archived from the original on 2000-10-25. Retrieved 24 June 2021.
"Molar mass of carbon-12". The NIST Reference on Constants, Units, and Uncertainty. May 2019. Archived from the original on 2000-12-06. Retrieved 24 June 2021.
"Proton mass in u". The NIST Reference on Constants, Units, and Uncertainty. May 2019. Archived from the original on 2000-12-07. Retrieved 24 June 2021.
"neutron mass in u". The NIST Reference on Constants, Units, and Uncertainty. May 2019. Archived from the original on 2000-12-07. Retrieved 24 June 2021.