I should say something would depend upon the family tradition of the other fellows to whom you refer. In ours gambling debts and shady transactions with turf-robbers happen to be forbidden luxuries.'
Books can be attributed to "Unknown" when the author or editor (as applicable) is not known and cannot be discovered. If at all possible, list at least one actual author or editor for a book instead of using "Unknown".
Books whose authorship is purposefully withheld should be attributed instead to Anonymous.