APA (7th ed.) Citation

Eckel, E. B., Milton, C., & Eckel, E. B. (1959). Geology and mineral resources of Paraguay: A reconnaissance.

Chicago Style (17th ed.) Citation

Eckel, Edwin B., Charles Milton, and Edwin B. Eckel. Geology and Mineral Resources of Paraguay: A Reconnaissance. Washington, 1959.

MLA (9th ed.) Citation

Eckel, Edwin B., et al. Geology and Mineral Resources of Paraguay: A Reconnaissance. 1959.