MLA

Ricke, Steven C, and Todd R Callaway. Direct-fed Microbials and Prebiotics for Animals. Springer New York, 2012.

APA

Ricke, S. C, & Callaway, T. R. (2012). Direct-Fed Microbials and Prebiotics for Animals. Springer New York.

Chicago

Ricke, Steven C., and Todd R Callaway. Direct-Fed Microbials and Prebiotics for Animals. : Springer New York, 2012.