APA (7th ed.) Citation

Wells, F. G., & Peck, D. L. Geologic map of Oregon west of the 121st meridian.

Chicago Style (17th ed.) Citation

Wells, Francis G., and Dallas L. Peck. Geologic Map of Oregon West of the 121st Meridian.

MLA (9th ed.) Citation

Wells, Francis G., and Dallas L. Peck. Geologic Map of Oregon West of the 121st Meridian.

Warning: These citations may not always be 100% accurate.