APA

Guardini R., . (1956). Sacred signs. St. Louis: Pio Decimo Press.

Chicago

Guardini Romano, . 1956. Sacred signs. St. Louis: Pio Decimo Press.

Harvard

Guardini R., . (1956). Sacred signs. St. Louis: Pio Decimo Press.

MLA

Guardini Romano, . Sacred signs. St. Louis: Pio Decimo Press. 1956.