APA (7e ed.) Bronvermelding

(1940). Key of heaven: A manual of prayers and instructions for Catholics, in accordance with recent pontifical decrees. Catholic Book Pub. Co..

Chicago (17e ed.) Bronvermelding

Key of Heaven: A Manual of Prayers and Instructions for Catholics, in Accordance with Recent Pontifical Decrees. New York: Catholic Book Pub. Co., 1940.

MLA (8e ed.) Bronvermelding

Key of Heaven: A Manual of Prayers and Instructions for Catholics, in Accordance with Recent Pontifical Decrees. Catholic Book Pub. Co., 1940.