Meggers, B. J., Evans, C., & Estrada, E. (1965). Early formative period of coastal Ecuador: The Valdivia and Machalilla phases. Smithsonian Institution.

Meggers, Betty Jane, Clifford Evans, and Emilio Estrada. Early Formative Period of Coastal Ecuador: The Valdivia and Machalilla Phases. Washington, D.C.: Smithsonian Institution, 1965.

Meggers, Betty Jane, et al. Early Formative Period of Coastal Ecuador: The Valdivia and Machalilla Phases. Smithsonian Institution, 1965.