William the Silent
For a quote to be considered sourced, there must be evidence that it was said by the person in question: a book, for example, which can trace the quote to its origin. The links do not provide this evidence. They merely allege that William said or wrote these words. As evidence, then, they are merely the equivalent of hearsay. The site in Dutch may, for all I know, provide evidence; but unless this can be demonstrated, it must be assumed that it does not.
A second point: sources should be provided in Wikiquote articles themselves and not through searching linked pages. Links aren't guaranteed to last; they may be broken or discontinued. Every sourced quote on a Wikiquote page should be accompanied by its source. In this case, since no sources have yet been provided, I will have to change them from Sourced to Unsourced. Best wishes. - InvisibleSun 22:52, 21 May 2008 (UTC)