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