APA

Olson S. L., .Revision of the northern forms of Euphonia xanthogaster (<Aves: Thraupidae>). : .

Chicago

Olson Storrs L, .Revision of the northern forms of Euphonia xanthogaster (<Aves: Thraupidae>). : .

Harvard

Olson S. L., .Revision of the northern forms of Euphonia xanthogaster (<Aves: Thraupidae>). : .

MLA

Olson Storrs L, .: . .