Youngken, H. W. (1921). A text book of pharmacognosy. P. Blakiston's son & co.
Lua i Stíl Chicago (17ú heag.)Youngken, Heber Wilkinson. A Text Book of Pharmacognosy. Philadelphia: P. Blakiston's son & co, 1921.
Lua MLA (8ú heag.)Youngken, Heber Wilkinson. A Text Book of Pharmacognosy. P. Blakiston's son & co, 1921.
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