Columbia subject headings:
Harvard subject headings:
Paleobotany--Holocene--Mexico.
Paleobotany--Mexico--Puebla de Zaragoza Region.
Paleobotany--Mexico--Tlaxcala de Xicohténcatl Region.
Paleobotany--Quaternary
Paleoclimatology--Mexico.
Palynology--Mexico--Puebla de Zaragoza Region--History.
Palynology--Mexico--Tlaxcala de Xicohténcatl Region.
Vegetation and climate--Mexico--Puebla de Zaragoza Region--History.
Vegetation and climate--Mexico--Tlaxcala de Xicohténcatl Region--History.
Princeton subject headings:
Paleobotany--Mexico--Puebla Region.
Paleobotany--Mexico--Tlaxcala de Xicohténcatl Region.
Paleobotany--Quaternary.
Palynology--Mexico--Puebla Region--History.
Palynology--Mexico--Tlaxcala de Xicohténcatl Region.
Vegetation and climate--Mexico--Puebla Region--History.
Vegetation and climate--Mexico--Tlaxcala de Xicohténcatl Region--History.