Book: Moyer, Dennis K. 1998 Fraktur Writings and Folk Art Drawings of the Schwenkfelder Library Collection.
• For biographical information and illustrations of Heÿdrich's bookplates and religious texts, see pp. 142-47.Article: Evans, Nancy Goyne. 03//1973 Documented Fraktur in the Winterthur Collection: Part II. Antiques. 103 (3): 539-49.
• Published as fig. 9, pp. 546-7.Book: Shelley, Donald A. 1961 The Fraktur-Writings or Illuminated Manuscripts of the Pennsylvania Germans. 23.
• For other works by Heydrich, see p. 179.Book: Earnest, Russell D. & Earnest, Corinne P. 1997 Papers for Birth Dayes: Guide to the Fraktur Artists and Scriveners. 2 vols. 909.
• Published on p. 391.Article: Minardi, Lisa. 2011 From Millbach to Mahantongo: Fraktur and Furniture of the Pennsylvania Germans. American Furniture. 2-119.
• Published: p. 91, fig. 131.