APA Style

Stilton, G., Cernuschi, C. (2007). Geronimo Stilton a very merry Christmas . New York, USA: Scholastic Inc.

MLA Style

Stilton, Geronimo., Cernuschi, Claudius. "Geronimo Stilton a very merry Christmas". New York, USA: Scholastic Inc, 2007. Text.