APA

Fitzpatrick J. W., Willard D. E., .Twenty-one bird species new or little known from the Republic of Colombia. : .

Chicago

Fitzpatrick J W, Willard David E, .Twenty-one bird species new or little known from the Republic of Colombia. : .

Harvard

Fitzpatrick J. W., Willard D. E., .Twenty-one bird species new or little known from the Republic of Colombia. : .

MLA

Fitzpatrick J W, Willard David E, .: . .