From the Wikipedia page [1]

ONE National Gay and Lesbian Archives, founded in 1952, is the oldest existing Lesbian, Gay, Bisexual and Transgender (LGBT) organization in the United States and the largest repository of LGBT materials in the world. Since 2010 ONE Archives has been a part of the University of Southern California Libraries.[2] ONE Archives collections contain over two million items. ONE Archives also operates a small gallery and museum space devoted to LGBT art and history in West Hollywood, California. Use of the collection is free during regular business hours.

ONE Archives originated from ONE, Inc., which began publishing the earliest national homosexual publication in 1952. In 1956, ONE Inc. created the ONE Institute, an academic institute for the study of homosexuality, utilizing the term “Homophile Studies.” In 1994, ONE, Inc. and the International Gay and Lesbian Archives run by Jim Kepner merged. Since 1994 the organization has operated solely as a LGBT archive.

The website is [2].