Gaya APA

Samuelsson, G. (1999). Drugs of Natural Origin: A Textbook of Pharmacognosy (4th.ed). Sweden: Apotekarsocieteten.

Gaya MLA

Samuelsson, Gunnar. "Drugs of Natural Origin: A Textbook of Pharmacognosy". 4th.ed Sweden: Apotekarsocieteten, 1999. Text.