Pellegrini russi e vagabondi mistici - Evdokimov, Michel. (OLS)http://ftis/name/57238 (Paoline, 1990)

Spirituality : Forms, Foundations, Methods - Waaijman, Kees. (OLS)http://ftis/name/67136; Vriend, John. (OLS)http://ftis/name/58948 (Peeters, 2002)