The Sidereal Year and the Celestial Caiman: Measuring Deep Time in Maya Inscriptions Michael Grofe Archaeoastronomy: The Journal of Astronomy in Culture, vol. XXIV, 2011 (released August, 2012).

https://www.academia.edu/49056463/Calendars_and_the_Mayan_time_an_astronomical_and_sociocultural_aspects_based_analysis_in_Book_of_Abstracts_25th_International_Congress_of_History_of_Science_and_Technology?rhid=28723763698&swp=rr-rw-wc-79605981