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.
Technically I read the New Testament on the Bible app, but I'm not religious so it's interesting reading it from a secular perspective because oh boy do I have criticisms on what's considered okay (see all the condoning slavery things, suppressing women too) and what's considered wrong (see divorce, being gay, and any sexual activity). It is interesting to read though.