@article{ITA_1989__23_2_217_0,
     author = {Degano, Pierpaolo and Gianni, Patrizia},
     title = {A normal form for restricted exponential functions},
     journal = {RAIRO - Theoretical Informatics and Applications - Informatique Th\'eorique et Applications},
     pages = {217--231},
     publisher = {EDP-Sciences},
     volume = {23},
     number = {2},
     year = {1989},
     mrnumber = {1001727},
     zbl = {0665.03018},
     language = {en},
     url = {http://www.numdam.org/item/ITA_1989__23_2_217_0/}
}