Esto, R. (1990). Book of riddles for students & professionals. R.E. Books Marketing.
Čikaški stil citiranja (17. izdanje)Esto, Rey. Book of Riddles for Students & Professionals. [S.l.]: R.E. Books Marketing, 1990.
MLA način citiranja (9. izdanje)Esto, Rey. Book of Riddles for Students & Professionals. R.E. Books Marketing, 1990.
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