On 2009‒03‒30, Thomas Krichel filed form i1023 and it’s attachment on behalf of the society.
On 2009‒07‒14, Robert Choi, Director, Exempt Organizations, Rulings and Agreements, at the Internal Revenue Service sent Thomas Krichel his Letter 947 (DO/CG). He wrote
we have determined that you are exempt from Federal income tax under section 501(c) (3) of the Internal Revenue Code. Contributions to you are deductible under section 170 of the Code. You are also qualified to receive tax deductible bequests, devises, transfers or gifts under section 2055, 2106 or 2522.
Other salient data of the letter are
We are grateful to the Internal Revenue Service for this recognition. On 2013‒05‒02, we used the IRS publication 78 search, clicked on “Are eligible to receive tax-deductible contributions”, filled in the Name field “"Open Library Society"”, and found our data registered there.