York, M. J., & Idle, M. S. (2013). The three billy goats gruff. Child's World.
Lua i Stíl Chicago (17ú heag.)York, M. J., agus Molly Schaar Idle. The Three Billy Goats Gruff. Mankato, MN: Child's World, 2013.
Lua MLA (8ú heag.)York, M. J., agus Molly Schaar Idle. The Three Billy Goats Gruff. Child's World, 2013.
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