Esto, R. (1990). Book of riddles for students & professionals. R.E. Books Marketing.
Chicago Style aipamenaEsto, Rey. Book of Riddles for Students & Professionals. [S.l.]: R.E. Books Marketing, 1990.
MLA aipamenaEsto, Rey. Book of Riddles for Students & Professionals. R.E. Books Marketing, 1990.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.