Never heard of him? Nor had I:
http://musicweb-international.com/classrev/2016/Mar/Dammerung_CD154.htm (http://musicweb-international.com/classrev/2016/Mar/Dammerung_CD154.htm)
Biography here:
https://en.wikipedia.org/wiki/Gerard_von_Brucken_Fock (https://en.wikipedia.org/wiki/Gerard_von_Brucken_Fock)
Details of the contents of his archive are to be found here:
http://www.nederlandsmuziekinstituut.nl/en/archives/list-of-music-archives?task=listhandschriften&tmpl=lexicon&id=030 (http://www.nederlandsmuziekinstituut.nl/en/archives/list-of-music-archives?task=listhandschriften&tmpl=lexicon&id=030)
Cello Sonata in e here:
https://www.youtube.com/watch?v=Y9dMRuUdjGs (https://www.youtube.com/watch?v=Y9dMRuUdjGs)
Jerry
Also a cd on Amazon (Marketplace), with several works for mezzo & piano.
http://www.amazon.com/Low-Tide-at-River-Scheldt/dp/B002E0DTFM/ref=sr_1_1?s=music&ie=UTF8&qid=1459126917&sr=1-1&keywords=Brucken+Fock (http://www.amazon.com/Low-Tide-at-River-Scheldt/dp/B002E0DTFM/ref=sr_1_1?s=music&ie=UTF8&qid=1459126917&sr=1-1&keywords=Brucken+Fock)
A very minor celebrity in the Netherlands - his Christmas Cantata was performed with some regularity during the first half of the 20th century, but to my knowledge the symphonies and the piano concerto were never performed. His brothers Abraham and Emile were composers too, the latter enjoying some fame with his successful opera Seleneia, which was performed during the opening season of the avant-garde Great Holland Opera house, together with Dopper's The Blind Man of Cuillé Castle (1894).
The Cello Sonata is very Brahmsian, but also very fine, with a wonderful range of expression. A worthwhile rediscovery indeed. The performance is spectacularly good. Do try this lovely music...