Books on the Angels
1. My Way - The best little book summarizing the teaching of the Angelic Doctor, St. Thomas Aquinas, on every subject, including angels.
2. The Angels - Fr. Pascal Parente
3. My Angel will go before you - George Huber
4. The Angels and their Mission - Cardinal Danielou, SJ
5. All about Angels - Paul Sullivan, OP
6. St. Michael and the Angels - various sources
7. Heavenly Army of Angels - Bob and Penny Lord
8. Angels (and Demons) - Peter Kreeft
9. The Angels are Waiting - Fr. Randall Paine, ORC
10. The World and Work of the Holy Angels - Fr. Robert Fox, Fátima Family Apostolate.
Most of these are available from Leaflet Missal Company; the balance from Stella Maris Books.
Leaflet Missal Company (1-800-328-9582), Stella Maris Books (1-800-772-5928).