Maunder, A. S. D. (1934). "The origin of the symbols of the planets". The Observatory. 57: 238–247. Bibcode:1934Obs....57..238M.
iau.org
Since at least 1988, the International Astronomical Union has deprecated use of planetary symbols in journal articles.The IAU Style Manual(PDF). The International Astrophysical Union. 1989. p. 27. Archived(PDF) from the original on 21 June 2018. Retrieved 20 August 2018.
imss.fi.it
brunelleschi.imss.fi.it
"Bianchini's planisphere". Florence, Italy: Istituto e Museo di Storia della Scienza (Institute and Museum of the History of Science). Retrieved 17 March 2010.
Since at least 1988, the International Astronomical Union has deprecated use of planetary symbols in journal articles.The IAU Style Manual(PDF). The International Astrophysical Union. 1989. p. 27. Archived(PDF) from the original on 21 June 2018. Retrieved 20 August 2018.
Koch, Rudolf (1955) [1930]. The book of signs : which contains all manner of symbols used from the earliest times by primitive peoples and early Christians. Translated by Vyvyan Holland. Dover. p. 18. ISBN9780486153902. OCLC1124412910.
Neubecker, Ottfried; Brooke-Little, J P (1976). Heraldry: Sources, Symbols, and Meaning. New York: McGraw-Hill. p. 142. ISBN9780070463080. OCLC1089555543.