@article{CMH_1968__43_139354,
     author = {J.T. Marti},
     title = {Operational {Calculus} for {Two} {Commuting} {Closed} {Operators.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {87--97},
     publisher = {mathdoc},
     volume = {43},
     year = {1968},
     zbl = {0155.46103},
     url = {http://geodesic.mathdoc.fr/item/CMH_1968__43_139354/}
}