APA (7th ed.) Citation

Parkhurst, D. L., Thorstenson, D. C., & Plummer, L. N. (1990). PHREEQE: A computer program for geochemical calculations (Rev. and repr. Aug. 1990.). U.S. Geological Survey.

Chicago Style (17th ed.) Citation

Parkhurst, David L., Donald C. Thorstenson, and L. Niel Plummer. PHREEQE: A Computer Program for Geochemical Calculations. Rev. and repr. Aug. 1990. Reston, Va.: U.S. Geological Survey, 1990.

MLA (9th ed.) Citation

Parkhurst, David L., et al. PHREEQE: A Computer Program for Geochemical Calculations. Rev. and repr. Aug. 1990. U.S. Geological Survey, 1990.