MLA

O'Brien, Richard James. A Descriptive Grammar of Ecclesiastical Latin Based On Modern Structural Analysis. Chicago: Loyola University Press, 1965.

APA

O'Brien, R. James. (1965). A descriptive grammar of ecclesiastical Latin based on modern structural analysis. Chicago: Loyola University Press.

Chicago

O'Brien, Richard James, A Descriptive Grammar of Ecclesiastical Latin Based On Modern Structural Analysis. Chicago: Loyola University Press, 1965.