[3] Assem, I., Simson, D., Skowroński, A.: 
Elements of the Representation Theory of Associative Algebras. Vol. 1: Techniques of Representation Theory. London Mathematical Society Student Texts 65. Cambridge University Press, Cambridge (2006). 
DOI 10.1017/CBO9780511614309 | 
MR 2197389 | 
Zbl 1092.16001