270.5 Late Middle Ages through Renaissance, 1200-1517
270.39 Great Schism, 1054
271 Religious Orders
This section includes works on a variety of religious orders and their rules but is not limited to medieval Christianity.
272 Persecutions in church history
This section contains resources concerning persecutions throughout church history. For medieval Christianity, pay specific attention to 271.2 (Inquisition).
273 Doctrinal Controversies and Heresies
For medieval Christanity, 273.4-273.6 are very useful.