Citation, Documentation of Sources

Q. I am currently copyediting a business-advice book that has a very casual, conversational tone. The book includes a bibliography, but so far, none of the quoted works mentioned in the text are in the bibliography. There are many sound bites from famous actors and writers. These one-liners are not necessarily well-known quotes, but considering that the people quoted are public figures and the quotes themselves are (in most cases) only a short sentence, is a source really needed? And then a bibliographic entry? It seems a bit excessive, but I don’t know how else to do this. Unfortunately, this book does not have notes. Any ideas?

A. Quotations from famous people must be attributed (to newspaper or magazine articles, blogs, online news sites, television or radio appearances, or whatever), but you needn’t include such sources in the bibliography.