91st PA: selected sources

Advance the colors: Advance the colors, pp.313-315. '91st Infantry'. (Includes a history of the flags and color bearers, and a bibliography.)
Bates: Bates, Samuel Penniman. History of Pennsylvania volunteers, 1861-5. Harrisburg: B. Singerly, state printer, 1869-71. 5 volumes. 'Ninety-first regiment', volume 3, pages 186-233. Transcription by Gary Steiner of the service summary. The complete text of Bates is available on University of Michigan's Making of America.
[Bates' service summaries are sometimes inaccurate. See, for example, special order 4, HQ 91st PA, 16 February 1864, which records transfers Bates missed. In some cases the transcriber may also have misread the handwriting; Frederick Henry, for example, seems to be Bates' Frederick Hentz.]
Dyer: Frederick H. Dyer. A compendium of the war of the rebellion. Reprint edition. New York: Thomas Yoseloff, 1959. 3 volumes.
OAR: Official Army Register
OR (Official Records): The war of the rebellion: a compilation of the official records of the Union and Confederate armies. Washington: Government Printing Office. (Explicit references to the 91st PA.)
Taylor: Frank H. Taylor. Philadelphia in the Civil War 1861 1865. Published by the city, 1913.
Walter: Thomas F. Walter. 'Personal recollections and experiences of an obscure soldier'. Grand Army Scout and Soldiers' Mail, volumes 3 number 34 (2 August 1884) to volume 4 number 3 (27 December 1884). (I do not yet have the instalments in volume 3 number 34, or volume 4 number 3.)
Welch: Joseph Welch. 'Dedication of monument: 91st regiment infantry. September 12, 1889.' Pennsylvania at Gettysburg: ceremonies at the dedication of the monuments erected by the Commonwealth of Pennsylvania. Volume 1, 1914. Pages 500-507.

Sources for the 91st Pennsylvania