Bergen, J. Y. (1904). Elements of botany (Rev. ed.). Ginn & company.
Lua i Stíl Chicago (17ú heag.)Bergen, Joseph Y. Elements of Botany. Rev. ed. Boston, [etc.]: Ginn & company, 1904.
Lua MLA (8ú heag.)Bergen, Joseph Y. Elements of Botany. Rev. ed. Ginn & company, 1904.
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