@article{700088,
     title = {On limit-point and separation criteria for linear differential expressions},
     booktitle = {Proceedings of Equadiff III},
     series = {GDML\_Books},
     publisher = {Univ. J. E. Purkyn\v e - P\v r\'\i rodov\v edeck\'a fakulta},
     address = {Brno},
     year = {1973},
     pages = {31-42},
     mrnumber = {MR0367354},
     zbl = {0329.34020},
     url = {http://dml.mathdoc.fr/item/700088}
}

Everitt, William Norrie; Giertz, Magnus. On limit-point and separation criteria for linear differential expressions, dans Proceedings of Equadiff III, GDML_Books,  (1973), pp. 31-42. http://gdmltest.u-ga.fr/item/700088/