Παραπομπή σε μορφή APA (7η εκδ.)

Koba, S., & Mitchell, C. T. (2011). Hard-to-teach science concepts: A framework to support learners, grades 3-5. National Science Teachers Association.

Παραπομπή σε μορφή Chicago (17η εκδ.)

Koba, Susan, και Carol T. Mitchell. Hard-to-teach Science Concepts: A Framework to Support Learners, Grades 3-5. Arlington, Va.: National Science Teachers Association, 2011.

Παραπομπή σε μορφή MLA (9th εκδ.)

Koba, Susan, και Carol T. Mitchell. Hard-to-teach Science Concepts: A Framework to Support Learners, Grades 3-5. National Science Teachers Association, 2011.