@article{1183530661, author = {Lee, Keean}, title = {A note on functors ${\text{Ext}}$ over the ring $Z$}, journal = {Bull. Amer. Math. Soc.}, volume = {75}, number = {5}, year = {1969}, pages = { 852-856}, language = {en}, url = {http://dml.mathdoc.fr/item/1183530661} }
Lee, Keean. A note on functors ${\text{Ext}}$ over the ring $Z$. Bull. Amer. Math. Soc., Tome 75 (1969) no. 5, pp. 852-856. http://gdmltest.u-ga.fr/item/1183530661/