In the preface to the 1964 edition of Mormonism: Shadow or Reality? the Tanners wrote of how various Latter-day Saint (often rather pro-LDS institutions, too, to boot) helped with their research:
The Mormon people have greatly assisted in the writing of this book. Some of them have allowed us access to their own research, others have helped in various ways. . . . The University of Utah Libtary has greatly assisted by allowing Verifax copies to be made of many of their rare books. The Utah State Historical Society has also been very helpful. The Yale University Library, the Mormon Church Genealogical Library, the Brigham Young University Library and the Salt Lake City Public Library have also provided help.
So much for the conspiracy theory that LDS institutions and groups will not assist even critics of the Church.