Davies, C. J. 1912. Fancy Mice, Fifth Edition. L Upcott Gill, London, UK.

Adult males, on the other hand, must be housed separately, for, if put together, they will fight to the death. As already mentioned, young males of the same litter if never separated from birth may live together for some time, the precise period depending upon the time of year and their state of maturity. When they begin to fight they must be separated, and this is likely to occur at an earlier period in the springtime and summer than among mice born later in the year.