The Great Year of the Maya: U Kokan Chan, K'uk' Bahlam I, and Contrived Intervals of the Sidereal Year and the Tropical Year in the Tablet of the Cross, Palenque Michael Grofe

https://www.academia.edu/49070287/The_Great_Year_of_the_Maya_U_Kokan_Chan_Kuk_Bahlam_I_and_Contrived_Intervals_of_the_Sidereal_Year_and_the_Tropical_Year_in_the_Tablet_of_the_Cross_Palenque