1. Åberg, H.: Coherence of amalgamations. J. Algebra 78(2), 372–385 (1982)
2. Bondal, A.I., Polishchuk, A.E.: Homological properties of associative algebras: the method of helices. Russian Acad. Sci. Izv. Math. 42(2), 219–260 (1994)
3. Bondal, A., Zhdanovskiy, I.: Representation theory for systems of projectors and discrete Laplace operators. IPMU13-0001, IPMU, Kashiwa, Japan (2013). http://db.ipmu.jp/ipmu/sysimg/ipmu/1012.pdf
4. Bourbaki, N.: Éléments de Mathématique. Algèbre. Chapitre 10. Algèbre Homologique. Masson, Paris (1980)
5. Chase, S.U.: Direct products of modules. Trans. Amer. Math. Soc. 97(3), 457–473 (1960)