DinnerFor11 proves that OP(3,3,5) has no solution. Despite the result is well known in literature, there is no proof other than a self-referencing unpublished paper.
The missinng proof
We quote the original source paper cited by most of the literature:
Of course, the ‘problem’ is to decide whether the above conjecture is true or false. (The first ‘exceptional case’, namely C(4,5)!=K(9), has been proven by several authors; in an unpublished paper  the author proved C(3,3,5)!=K(11) with the aid of a computer.)
 W.L. Piotrowski, Untersuchungen iiber das Oberwolfacher Problem, 1979, manuscript
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