There are only three commemorative stamps of 1941, not six.

In any case, it is considered by some as America's first commemorative stamp.

A post office was opened for one day to issue commemorative stamps.

Its commemorative stamps are among the finest to be found.

We use in the book about 10 percent of all commemorative stamps that were issued.

It was the third set of British commemorative stamps issued in 2006.

A commemorative stamp was also issued on January 31, 1987.

The next commemorative stamp to honor Grant was the 32-cent issue of 1995.

It is one among only two commemorative stamps that honor this president.

Another commemorative stamp was published on the 90th anniversary of the series in 2009.