Fifield, Christopher. Friedrich Gernsheim at Google Books. “The German Symphony 1870-1876” in The German Symphony Between Beethoven and Brahms: The Fall and Rise of a Genre. Farnham, VT. Ashgate Publishing Co: 2015. p.254
This opus number differs from that under Gernsheim on List of compositions for cello and piano, which bases its information on Muller-Reuter's Lexicon (which is referring to the 2nd sonata above, and Op.79). Some confusion seems to have arisen because authors of a concert brochure may have forgotten the existence of the 2nd sonata when they gave the premiere or modern premiere of this 3rd sonata of 1914.