@article{700218,
     title = {On linear differential equations of higher odd order},
     booktitle = {Differential Equations and Their Applications},
     series = {GDML\_Books},
     publisher = {Slovensk\'e pedagogick\'e nakladate\v lstvo},
     address = {Bratislava},
     year = {1967},
     pages = {81-88},
     zbl = {0185.15904},
     url = {http://dml.mathdoc.fr/item/700218}
}

Greguš, M. On linear differential equations of higher odd order, dans Differential Equations and Their Applications, GDML_Books,  (1967), pp. 81-88. http://gdmltest.u-ga.fr/item/700218/