Just a quick note of an interesting tidbit. There seems to be no instance in which Athanasius uses the term 'apocrypha' to mean what we think that term should mean (= non-canonical literature) outside of his famous 39th Festal Letter.
I ran a TLG search for forms of the word "apocrypha" in Athanasius, which returned 19 hits. But more than half of these were related to spurious works of Athanasius. Of the eight hits from legitimate works from Athanasius, 3 were from his Festal Letter, one was from another letter called Epistula ad episcopos Aegypti et Libyae, and four were from his Expositions of the Psalms (PG 27).
The one from the Epistula ad episcopos Aegyti et Libyae is just a quotation of Colossians 2:3, "in whom are hidden (ἀπόκρυφοι) all the treasures of wisdom and knowledge."
The four from the Expositions of the Psalms all carry the meaning "hidden" (not about a book) and two are just quoting the psalm under discussion (LXX Psa. 30:21; 80:8; the others are in discussions of LXX Psa. 16:14; 32:11)
The 39th Festal Letter actually uses the word "apocrypha" ten times, but only three of these are preserved in Greek. Most of the letter is preserved in Coptic. For a full translation of the letter, see the recent article by David Brakke in HTR 2010. The appearances of the word apocrypha in this letter, accordinng to the paragraph divisions employed by Brakke, are in paragraphs 15, 16, 21 (3x), 22, 26, 27, 28, 32. The first three of these are the ones preserved in Greek.