@article{JEDP_1981____A5_0,
     author = {Stein, Elias M.},
     title = {Compositions of pseudo-differential operators},
     journal = {Journ\'ees \'equations aux d\'eriv\'ees partielles},
     eid = {5},
     pages = {1--6},
     publisher = {Ecole polytechnique},
     year = {1981},
     language = {en},
     url = {http://www.numdam.org/item/JEDP_1981____A5_0/}
}