APA

walker R. D., MAHURIN M., . (2005). once upon a cloud. new york: the blue sky press.

Chicago

walker ROB D, MAHURIN MATT, . 2005. once upon a cloud. new york: the blue sky press.

Harvard

walker R. D., MAHURIN M., . (2005). once upon a cloud. new york: the blue sky press.

MLA

walker ROB D, MAHURIN MATT, . once upon a cloud. new york: the blue sky press. 2005.