Rosalind Wiseman (2013). “Masterminds and Wingmen: Helping Our Boys Cope with Schoolyard Power, Locker-Room Tests, Girlfriends, and the New Rules of Boy World”, p.37, Harmony
Johann Wolfgang von Goethe (1989). “Conversations of German Refugees ; Wilhelm Meister's Journeyman Years, Or, The Renunciants”, p.296, Princeton University Press