APA

Packard J. M., Summers R. C. & Barnes L. B.Variation of visibility bias during aerial surveys of manatees. : .

Chicago

Packard Jane M, Summers Robert C and Barnes Lindsay B.Variation of visibility bias during aerial surveys of manatees. : .

Harvard

Packard J. M., Summers R. C. and Barnes L. B.Variation of visibility bias during aerial surveys of manatees. : .

MLA

Packard Jane M, Summers Robert C and Barnes Lindsay B.: . .