Search Loci: Convergence:
[T]he student skit at Christmas contained a plaintive line: "Give us Master's exams that our faculty can pass, or give us a faculty that can pass our Master's exams."
I Want to Be a Mathematician, Washington: MAA Spectrum, 1985.
When a Number System Loses Uniqueness: The Case of the Maya
 Ascher, M., Before the Conquest, Mathematics Magazine, Vol. 65, No. 4, Oct., 1992, pp. 211-218.
 Cooke, R., The History of Mathematics: A Brief Course, 2nd ed., Wiley-Interscience, John Wiley & Sons, 2005.
 Katz, V. J., A History of Mathematics: An Introduction, 3rd ed., Addison-Wesley, 2009, p. 270.
 Morley, S. G., An Introduction to the Study of the Maya Hieroglyphs, 57, Smithsonian Institution Bureau of American Ethnology, Government Printing Office, 1915. Also available from Google Books.
 Maya Info: Ring and Serpent Dates in the Dresden Codex, www.mayainfo.org/works/ring/default.asp
 Mundo Maya: Mayan Codices, www.mayadiscovery.com/ing/history/codices.htm
 The Maya Astronomy Page: Maya Calendar, www.michielb.nl/maya/calendar.html
 Maya Exploration Center, http://mayaexploration.com/staff_barnhart.php
Maya Calendar Conversions, by Ximena Catepillan and Waclaw Szymanski (2010)
Maya Cycles of Time, by Sandra Monteferrante (2007)
Shell-Gellasch, Amy and Pedro J. Freitas, "When a Number System Loses Uniqueness: The Case of the Maya," Loci (May 2012), DOI: 10.4169/loci003883