The cover has three kinds of stamps.
The first one on the left was issued last November 14, 2009 and the illustration is about National Children Drawing Contest on the theme “I Can Slow TB Down.”
The second set of stamps was issued last August 28. 2010 about Argentina’s Traditional Games - Bowls and "Truco" – a very popular card game in the Americas. This issue has the Postal Union of the Americas, Spain and Portugal (UPAEP) logo in it.
The third stamp that was issued this year talks about the 200 years (bicentenary) celebration of May Revolution - 200 years of National Library. The May Revolution (Spanish: Revolución de Mayo) was a week-long series of revolutionary events that took place from May 18 to May 25, 1810, in Buenos Aires, capital of the Viceroyalty of the Río de la Plata, a colony of the Spanish Empire which included the present-day nations of Argentina, Bolivia, Paraguay and Uruguay.
Set of stamps are also included inside:
1. May Revolution - http://en.wikipedia.org/wiki/May_Revolution
2. Argentina Post Office - http://www.correoargentino.com.ar/filatelia/2010.php