APA
Ratzinger J., . (1970). Introduction to Christianity. New York: Herder & Herder.
Chicago
Ratzinger Joseph, . 1970. Introduction to Christianity. New York: Herder & Herder.
Harvard
Ratzinger J., . (1970). Introduction to Christianity. New York: Herder & Herder.
MLA
Ratzinger Joseph, . Introduction to Christianity. New York: Herder & Herder. 1970.
