Neeman, Amnon (2002). "A counterexample to a 1961 "theorem" in homological algebra". Inventiones mathematicae. 148: 397–420. doi:10.1007/s002220100197.
Daniel Frohardt and Kay Magaard, Composition Factors of Monodromy Groups, Annals of Mathematics Second Series, Vol. 154, No. 2 (Sep., 2001), pp. 327–345. Published by: Mathematics Department, Princeton University DOI: 10.2307/3062099 JSTOR3062099