@article{AIF_1992__42_1-2_275_0,
     author = {Haefliger, Andr\'e},
     title = {Extension of complexes of groups},
     journal = {Annales de l'Institut Fourier},
     pages = {275--311},
     publisher = {Institut Fourier},
     address = {Grenoble},
     volume = {42},
     number = {1-2},
     year = {1992},
     doi = {10.5802/aif.1292},
     mrnumber = {93j:20080},
     zbl = {0762.20018},
     language = {en},
     url = {http://www.numdam.org/articles/10.5802/aif.1292/}
}