@article{10_1090_S1079_6762_99_00060_8,
     author = {Mitrea, Marius},
     title = {On {Bojarski\^a€™s} index formula for nonsmooth interfaces},
     journal = {Electronic research announcements of the American Mathematical Society},
     pages = {40--46},
     publisher = {mathdoc},
     volume = {05},
     year = {1999},
     doi = {10.1090/S1079-6762-99-00060-8},
     url = {http://geodesic.mathdoc.fr/articles/10.1090/S1079-6762-99-00060-8/}
}