Παραπομπή APA

Onkar singh et al. (1993). Frontiers in environmental geography. Concept Publishing Company.

Παραπομπή Chicago Style

Onkar singh et al. Frontiers in Environmental Geography. New Delhi: Concept Publishing Company, 1993.

Παραπομπή MLA

Onkar singh et al. Frontiers in Environmental Geography. Concept Publishing Company, 1993.