@article{10_4064_ap_34_3_289_316,
     author = {Andrzej Karafiat},
     title = {The problem of the number of switches in parabolic equations with control},
     journal = {Annales Polonici Mathematici},
     pages = {289--316},
     publisher = {mathdoc},
     volume = {34},
     number = {3},
     year = {1977},
     doi = {10.4064/ap-34-3-289-316},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap-34-3-289-316/}
}