It seems a little strange that these should be mentioned specifically in the regulation, but there seems to be no doubt that this is what "estampas de álbumes" are, in Mexico and elsewhere.

"al menos en México, las estampas de álbumes escolares se refiere a las estampitas que los niños compran e intercambian (no a álbumes que sean parte de los libros de la escuela) [...] estas estampitas en inglés son "trading cards""
http://www.proz.com/kudoz/spanish_to_english/other/1150994-d...

"Alguien sabe cómo puedo conseguir estampas de Albumes q no se completaron??
Quiero llenar mi album d Avatar! jeje pero ya no venden las estampas en los puestos d periódicos!!! se les acabaron"
http://es.answers.yahoo.com/question/index?qid=2008022822324...

"Les traigo a la venta estampas de álbumes de Panini"
http://articulo.mercadolibre.com.mx/MLM-52531917-estampas-pa...

"Learning how to protect your NFL football collector cards will enable you to enjoy them for years to come or to re-sell at a higher value."
http://www.associatedcontent.com/article/1062507/tips_for_pr...

"9 Pocket Storage Sheets for Baseball, Football, Basketball, Hockey, Yugioh, Pokemon and Other Collector Cards"
http://thehockeyreviewsite.com/1794/100-bcw-9-pocket-storage...

"Offering Trading Cards for all sports including - Baseball Cards, Basketball Cards, Hockey Cards, Football Cards and more."
http://www.dcssportscards.com/

"FootballCardShop.com features a wide selection of football trading cards, including rookie cards, team sets and graded cards."
http://www.footballcardshop.com/

The term is sometimes used to refer to album stickers (with adhesive on the back), but these are properly called pegatinas (or cromos, at least in Spain).