[Aztlan] veintena

[macehual08 at gmail.com]

Hello,Could anyone tell me who coined the term "veintena" to describe the 18
"months" of the xihuitl "calendar"? Or anything about how or when it came
into scholarly use?

Alternatively, do you know who among the earliest chroniclers used the term?
(Sahagún, for example, seems mostly to use the term "mes.")

Thanks.
Paul