@article{SF_1993__47_2_135281,
     author = {F. Blanchet-Sadri},
     title = {Equations and dot-depth one.},
     journal = {Semigroup forum},
     pages = {305--317},
     publisher = {mathdoc},
     volume = {47},
     number = {2},
     year = {1993},
     zbl = {0814.20048},
     url = {http://geodesic.mathdoc.fr/item/SF_1993__47_2_135281/}
}