APA (7th ed.) Citation

Clark, . P., & Landfield, . J. (1976). Natural energy workbook (Rev. ed.). Visual Purple.

Chicago Style (17th ed.) Citation

Clark, Peter, and Judy Landfield. Natural Energy Workbook. Rev. ed. Berkeley: Visual Purple, 1976.

MLA (9th ed.) Citation

Clark, Peter, and Judy Landfield. Natural Energy Workbook. Rev. ed. Visual Purple, 1976.