Source:

Milliken, Randall, Richard T. Fitzgerald, Mark G. Hylkema, Randy Groza, Tom Origer, David G. Bieling, Alan Leventhal, Randy S. Wiberg, Andrew Gottsfield, Donna Gillette, Viviana Bellifemine, Eric Strother, Robert Cartier and David A. Fredrickson
2007   Punctuated Culture Change in the San Francisco Bay Area. In California Prehistory: Colonization, Culture, and Complexity, edited by Terry L. Jones and Kathryn A. Klar, pp. 99-123. AltaMira Press, Lanham, Maryland.

Dating Scheme D is described as "a pan-central California sequence of directly dated Olivella shell bead horizons" (Milliken et al. 2007:103-105). Dates are based on "calibrated radiocarbon dates and absolute time" and expressed in years B.P., understood here to mean years before A.D. 1950.