APA
World Health Organization, . (1989). Pyrrolizindine alkaloids health and safety guide. World Health Organization, Geneva: .
Chicago
World Health Organization, . 1989. Pyrrolizindine alkaloids health and safety guide. World Health Organization, Geneva: .
Harvard
World Health Organization, . (1989). Pyrrolizindine alkaloids health and safety guide. World Health Organization, Geneva: .
MLA
World Health Organization, . Pyrrolizindine alkaloids health and safety guide. World Health Organization, Geneva: . 1989.