Παραπομπή APA

Hawley, M. E. (1976). Coal, part 1: Social, economic and environmental aspects. Dowden Hutchinson And Ross.

Παραπομπή Chicago Style

Hawley, M E. Coal, Part 1: Social, Economic and Environmental Aspects. Pennsylvania: Dowden Hutchinson And Ross, 1976.

Παραπομπή MLA

Hawley, M E. Coal, Part 1: Social, Economic and Environmental Aspects. Dowden Hutchinson And Ross, 1976.