Yucatan Before and After the Conquest by Diego de Landa, tr. William Gates [1937]
The best primary source on the Maya, ironically by the monk who burned most of their books.

The Book of Chilam Balam of Chumayel by Ralph L. Roys [1930]

The Mayan Calendar

The Book of the People: Popol Vuh
by Delia Goetz and Sylvanus Griswold Morley from Adrián Recino's translation from Quiché into Spanish [1954, copyright not registered or renewed]

Maya Hieroglyphic Writing (excerpts)
by J. Eric S. Thompson [1950]

The Popul Vuh excerpt from The Mythic and Heroic Sagas of the Kichés of Central America, by Lewis Spence; London [1908] 79,023 bytes

The Myths of Mexico and Peru by Lewis Spence