APA Format
World Health Organization (WHO) . (). Pyrrolizidine alkaloids. : Geneva WHO 1988
MLA Format
World Health Organization (WHO) . Pyrrolizidine alkaloids. : Geneva WHO 1988,
Australian/Harvard Format
World Health Organization (WHO) . . Pyrrolizidine alkaloids. Geneva WHO 1988, 
Warning: These citations may not always be 100% accurate.