APA
Percival J., . (1921). Agricultural Botany. London: Duckworth & Co.
Chicago
Percival John, . 1921. Agricultural Botany. London: Duckworth & Co.
Harvard
Percival J., . (1921). Agricultural Botany. London: Duckworth & Co.
MLA
Percival John, . Agricultural Botany. London: Duckworth & Co. 1921.