Phebe Swan's Gleaners' Library wasn't the only reference by mail library. The H. W. Wilson Company began publishing the Readers Guide to Periodical Literature in 1901. When Swan developed her reference by mail library in 1902 she relied heavily on this publication and the periodicals which it indexed. At some point either before or after Swan's library started loaning periodical articles by mail, the H. W. Wilson Company launched its Cumulative Reference Library which also loaned periodical articles by mail for a fee. The postal card above is an interesting postal item in that it has been sent through the mail on two occasions. It was initially mailed as an invoice by the H. W. Wilson Company to the Defiance Public Library in Ohio on March 11, 1908. The card was returned to Wilson with a 15 cent payment in a separate envelope. Wilson then mailed the card back to the library as a receipt for payment on March 17, 1908 with a one cent stamp affixed over the original pre-stamped one cent postage indicia.