@article{CMH_1971__46_139462,
     author = {Wolfgang Wasow},
     title = {The {Central} {Connection} {Problem} at {Turning} {Points} of {Linear} {Differential} {Equations}},
     journal = {Commentarii mathematici Helvetici},
     pages = {65--86},
     publisher = {mathdoc},
     volume = {46},
     year = {1971},
     zbl = {0211.11001},
     url = {http://geodesic.mathdoc.fr/item/CMH_1971__46_139462/}
}