Books can be attributed to "Anonymous" for several reasons:
* They are officially published under that name * They are traditional stories not attributed to a specific author * They are religious texts not generally attributed to a specific author
Books whose authorship is merely uncertain should be attributed to Unknown.
pretty boring anti-tobacco tract (James I's "A Counterblaste to Tobacco" was better, as was Richard Brathwait's "Smoaking Age"). It argues mostly within the framework of humoral theory though. So if that interests you, then you may like this.