Gaya APA
S., P, D. (1990).
Letters 31-60. Transl. & preface by Owen J. Blum. .
Washington:
Washington Catholic University of America Press.
Gaya MLA
S., Petrus, Damianus,.
"Letters 31-60. Transl. & preface by Owen J. Blum. ".
Washington:
Washington Catholic University of America Press,
1990.
Buku.