Study arguing that Edwin Rushton, not Joseph Smith, was the ultimate source of the White Horse Prophecy.
Don L. Penrod, "Edwin Rushton as the Source of the White Horse Prophecy," BYU Studies 49, no. 3 (2010): 75-131
"This article publishes for the first time the two documents that are the basis for the white horse prophecy. One document is in the handwriting of Edwin Rushton and presumably predates the other, which is in an unidentified hand but is signed by Edwin Rushton. Both are undated. These documents are here presented in their entirety to demonstrate that Rushton’s original text underwent significant revision prior to its being circulated among Latter-day Saints as a prophecy. Transcripts of both documents follow on pages 116 to 126. This article gives the history of the documents, narrows the range of likely dates in which they could have been created, and examines problematic claims in the text of the documents. By these examinations, this article strives to demonstrate the unreliability of the Rushton documents as an accurate record of the words of Joseph Smith."
Don L. Pedrod's BYU Studies article showing that there are various anachronisms and other historical errors with the White Horse Prophecy, and that the evidence points to Edwin Rushton, not Joseph Smith, being the source thereof.