@article{GDZPPN002065614,
title = {Cohomology with free coefficients of the fundamental group of a graph of groups.},
journal = {Commentarii mathematici Helvetici},
volume = {60},
year = {1985},
pages = {31-45},
zbl = {0584.20037},
url = {http://dml.mathdoc.fr/item/GDZPPN002065614}
}
Brown, Kenneth S.; Geoghegan, Ross. Cohomology with free coefficients of the fundamental group of a graph of groups.. Commentarii mathematici Helvetici, Tome 60 (1985) pp. 31-45. http://gdmltest.u-ga.fr/item/GDZPPN002065614/