Cartwright, Mark (November 23, 2015). "Aztec Society". Ancient History Encyclopedia. Ancient History Encyclopedia Limited. Retrieved April 17, 2016.
Cartwright, Mark (February 26, 2014). "Aztec Civilization". Ancient History Encyclopedia. Ancient History Encyclopedia Limited. Retrieved April 17, 2016.
According to Aztec codices: Figure A means Atoctli (sediment by water); Figure B means Tlacotli (expensive); Figure C means Ixpouhqui (withered); Figure D means Xalteyo (sandy); Figure E means Tlacemolotlalli (inherited land); Figure F means Petlauhtl (uncovered); Figure G means Ocotla (pine wood); Figure H means Zacatl (grass) and Figure I means Teuhtli (dust).[16]