APA

Olson S. L., .Geographic variation in Chlorospingus ophthalmicus in Colombia and Venezuela (<Aves: Thraupidae>). : .

Chicago

Olson Storrs L, .Geographic variation in Chlorospingus ophthalmicus in Colombia and Venezuela (<Aves: Thraupidae>). : .

Harvard

Olson S. L., .Geographic variation in Chlorospingus ophthalmicus in Colombia and Venezuela (<Aves: Thraupidae>). : .

MLA

Olson Storrs L, .: . .