Have a blessed day
Curt Teich Co. published and printed cards from 1900 - to about 1978. They kept record of the millions of cards they produced by using a combination of letters and numbers indicating the series and date published; most of their cards use this system but there are a few outliers that do not. Since this company had been so consistent using production numbers dating them is relatively easy.
Here are some examples in using this system for Curt Teich cards:
*Note click the card to better read the details about the dating system
This link will take you to a list of production numbers an their corresponding dates. A very useful tool for collectors. http://www.lcfpd.org/docs/teich_guide_dating.pdf