Evangelical & Reformed Historical Society (German Reformed Church)

From the Wikipedia page on the Evangelical and Reformed Church.

The Evangelical and Reformed Church (E&R) was a Protestant Christian denomination in the United States. It was formed in 1934 by the merger of the Reformed Church in the United States (RCUS) with the Evangelical Synod of North America (ESNA). A minority within the RCUS remained out of the merger in order to continue the name Reformed Church in the United States. In 1957, the Evangelical and Reformed Church merged with the majority of the Congregational Christian Churches (CC) to form the United Church of Christ (UCC).

The website of the historical society is.