Ludwig Van Beethoven, John Trie (2017). “Ludwig Van Beethoven for Classical Guitar - Tablature: Arranged for Guitar by John Trie”, p.36, BoD - Books on Demand
"Essai sur le théorie des proportions chimiques" by Jons Jacob Berzelius (1819) translated in Henry M. Leicester and Herbert S. Klickstein "A Source Book in Chemistry 1400-1900" (p. 260), 1952.