Please answer a question about the following article about Dwight D. Eisenhower:

The development of the appreciation medals was initiated by the White House and executed by the Bureau of the Mint through the U.S. Mint in Philadelphia. The medals were struck from September 1958 through October 1960. A total of twenty designs are cataloged with a total mintage of 9,858. Each of the designs incorporates the text "with appreciation" or "with personal and official gratitude" accompanied with Eisenhower's initials "D.D.E." or facsimile signature. The design also incorporates location, date, and/or significant event. Prior to the end of his second term as President, 1,451 medals were turned-in to the Bureau of the Mint and destroyed. The Eisenhower appreciation medals are part of the Presidential Medal of Appreciation Award Medal Series.

During what period were the appreciation medals minted?
September 1958 through October 1960