¹ Naturally occurring isotope abundances: Commission on Atomic Weights and Isotopic Abundances report of the International Union of Pure and Applied Chemistry in Isotopic Compositions of the Elements 1989, Pure and Applied Chemistry, 70, 217.

² The Origin of Stoichiometry Problems. Jensen, W; J. Chem. Edu., 2003, 80, 1248.

³ http://www.kentchemistry.com/links/GasLaws/Mole.htm

⁴ Jeremias Benjamin Richter: Darmstaedter, L; Oesper, R. E.; J. Chem. Educ. 1928, 5, 785.

⁵ http://beryllium.imascientist.org.au/2012/05/23/dont-fish-scales-get-put-in-lipstick/

⁶ http://www.nobelprize.org/nobel_prizes/chemistry/laureates/1922/aston-bio.html

⁷ http://www.nasa.gov/mission_pages/apollo/missions/apollo13.html

⁸ http://science.ksc.nasa.gov/history/apollo/apollo-13/apollo-13.html