APA

Ptiman R. L., Stear L. R. & Force M. P.Marine birds of Malpelo island, Colombia. : .

Chicago

Ptiman Robert L, Stear Larry R and Force Michael P.Marine birds of Malpelo island, Colombia. : .

Harvard

Ptiman R. L., Stear L. R. and Force M. P.Marine birds of Malpelo island, Colombia. : .

MLA

Ptiman Robert L, Stear Larry R and Force Michael P.: . .