Information is from Mary Veldran DeWitt’s “The DeWitt Genealogy: Descendants of Tjereck Claessen DeWitt of Ulster County, New York.”
Further notes from Andries DeWitt Bible (not available in print, but see photos at link above and on Andries’ page), courtesy of the Matthew Ten Eyck DeWitt Family Collection.
Baptismal and Marriage Registers of the Old Dutch Church of Kingston, Ulster County, New York (formerly named Wiltwyck, and often familiarly called Esopus or ’Sopus), for One Hundred and Fifty Years from their commencement in 1660. Transcribed and edited by Roswell Randall Hoes, Chaplain U.S.N., corresponding secretary of the New York Genealogical and Biographical Society, etc. New York 1891; original publication De Vinne Press, New York; available today from Higginson Book Co., Salem, Mass., 508-745-7170. Detailed information about baptisms has been filled in through the end of 1687, marriages through 1701. More information is available. Records begin 1660. Other baptisms may have taken place in Hurley and other locations nearby; also from time to time itinerant ministers would travel through and perform various rites, not always entered in the books.
This is available online at archive.org.
Thomas Grier Evans, The De Witt Family of Ulster County, New York (reprinted from the New York Genealogical and Biographical Record, October 1886), New York: Trow’s Printing and Bookbinding Co., 201-213 East Twelfth Street, 1886. Available online from archive.org.
Marbletown, New York, baptism records at archive.org.
Ulster County, N. Y., Probate Records, In the Office of the Surrogate, and in the County Clerks Office at Kingston, N. Y., compiled, abstracted and translation by Gustave Anjou, Ph. D., 1906. Privately published (?) in New York, but available at genealogical libraries (NYPL and others). Subtitle: “A careful abstract and translation of the Dutch and English wills, letters of administration after intestates, and inventories from 1665, with genealogical and historical notes, and list of Dutch and Frisian baptismal names with their English equivalents.” Introduction by Judge A[lphonso] T[rumpbour] Clearwater, LL.D. This is available in reprinted form. Note that there are two distinct volumes included in this work, sometimes combined into one physical book.
WikiTree page on Col. Abraham Swits (see above) recommends Baptisms Schenectady Reformed Church 1694-1811 published by Kinship in 1987, also Pearson’s First Families of Schenectady, p. 186. I have not had a chance to go find these yet.