@book{AST_1998__249__R1_0,
     author = {Auscher, Pascal and Tchamitchian, Philippe},
     title = {Square root problem for divergence operators and related topics},
     series = {Ast\'erisque},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {249},
     year = {1998},
     mrnumber = {1651262},
     zbl = {0909.35001},
     language = {en},
     url = {http://www.numdam.org/item/AST_1998__249__R1_0/}
}