About the phoenix
These scans are from The Book of Beasts: Being a Translation from a Latin Bestiary of the Twelfth Century; translated by T.H. White. This book has been on a shelf in any home I've been in for most of the my life. The translator, T.H. White wrote The Once and Future King which inspired both the musical Camelot and Disney's animated Sword in the Stone.
A "Bestiary" was a medieval encyclopedia of creatures. Because of the time and beliefs of the authors, most bestiaries incorporated Christian moral lessons. Some books within Harry Potter's world, like The Monster Book of Monsters, could also be called bestiaries.
Books of beasts are dear to me, especially now that I'm writing a comic strip of Beasts. I've quoted some paragraphs from the entry about the phoenix, which may tell you some secrets about the Snoof's friend and client, Claremont (who first appears here).
A good, low price, reprint of The Book of Beasts can be bought from the good folks at Dover Books.