Found in some Bibles but not in others, this collection of writings is from the Greek for "hidden things"
Some 
Christians, notably the Roman Catholic and Eastern Orthodox churches, ... Law 
and Prophets sections, the Writings do not constitute a unity, but their very variety 
has made... [DOC] [TLE] Apocrypha and Pseudepigrapha - Oxford Biblical Studies Online [PAR] The Psalms of Solomon also is found in manuscripts of the Greek Bible but is not 
... as canonical scriptures, although some were more widely accepted than others
.