* Prestwich, M., "The Three Edwards: War and State in England, 1272–1377", 1980* Ramsay, J. H., "The Genesis of Lancaster", 1307–99, 1913.
* Prestwich, M., "The Three Edwards: War and State in England, 1272—1377", 1980* Ramsay, J. H., "The Genesis of Lancaster", 1307-99, 1913.