The etymological connection between the English adjective wise and the German verb wissen tracing back to the Proto-Indo-European root *weid- ("to see" or "to know") is a standard linguistic fact that requires no citation.
The claim is a well-established etymological fact about Germanic languages and Proto-Indo-European shared vocabulary (both descend from *weid-). As a matter of standard linguistic definition and historical grammar, it is common knowledge, so no retrieval papers are attached.