Croll, Philip Columbus; Schuler, Henry Addison; Kriebel, Howard Wiegner (January 1907). "Rev. Isaac K. Funk, D.D., LL.D."The Pennsylvania-German. VIII (I): 29. Retrieved February 15, 2014.
Lambert, J. (2014). "A Much Tortured Expression: A New Look at 'Hobson-Jobson'". International Journal of Lexicography. 27: 54–88. doi:10.1093/ijl/ect037.
newspapers.com
"Chicago Mediums Said to Have Duped Isaac Funk". Chicago Daily Tribune. Chicago, Illinois. February 25, 1905. p. 3. Dr. Isaac Funk of the publishing house of Funk & Wagnalls of New York has just paid the Bangs sisters 1500 for spirit painting.