@article{MS2_1962__10_165798,
     author = {Kai Lai Chung},
     title = {On the {Exponential} {Formulas} of {Semi-Group} {Theory.}},
     journal = {Mathematica Scandinavica},
     pages = {153--162},
     publisher = {mathdoc},
     volume = {10},
     year = {1962},
     zbl = {0106.31201},
     url = {http://geodesic.mathdoc.fr/item/MS2_1962__10_165798/}
}