Gaya APA
Purcell, J, H., Leppien, J, H. (2011).
Parallel curriculum units for mathematics grades 6-12 .
Thousand Oaks, California:
Corwin Sage.
Gaya MLA
Purcell, Jeanne, H.., Leppien, Jann, H..
"Parallel curriculum units for mathematics grades 6-12".
Thousand Oaks, California:
Corwin Sage,
2011.
Text.