APA

Nicolay H., . (1949). Lincoln's secretary. New York [u.a.]: Longmans, Green and Co.

Chicago

Nicolay Helen, . 1949. Lincoln's secretary. New York [u.a.]: Longmans, Green and Co.

Harvard

Nicolay H., . (1949). Lincoln's secretary. New York [u.a.]: Longmans, Green and Co.

MLA

Nicolay Helen, . Lincoln's secretary. New York [u.a.]: Longmans, Green and Co. 1949.