There are 1 book by M. J. C. O'Callaghan on BookOrb. A strong starting point is Separatism in Brittany (1983). The bibliography below is in publication order, with series grouped in reading order.
Standalone books
Frequently asked questions
How many books has M. J. C. O'Callaghan written?
BookOrb lists 1 book by M. J. C. O'Callaghan.
Where should I start with M. J. C. O'Callaghan?
A good starting point is Separatism in Brittany (1983).
What is the M. J. C. O'Callaghan books in order list?
In publication order: 1. Separatism in Brittany (1983).