Gaya APA

Purcell, J, H., Leppien, J, H. (2010). Parallel curiculum units for social studies grade 6-12 . Thousand Oaks, California: Corwin Sage.

Gaya MLA

Purcell, Jeanne, H.., Leppien, Jann, H.. "Parallel curiculum units for social studies grade 6-12". Thousand Oaks, California: Corwin Sage, 2010. Text.