@article{700199,
     title = {Some boundary problems for the equations with strong degeneration},
     booktitle = {Differential Equations and Their Applications},
     series = {GDML\_Books},
     publisher = {Slovensk\'e pedagogick\'e nakladate\v lstvo},
     address = {Bratislava},
     year = {1967},
     pages = {121-127},
     zbl = {0187.04001},
     url = {http://dml.mathdoc.fr/item/700199}
}

Nikolskij, S. Some boundary problems for the equations with strong degeneration, dans Differential Equations and Their Applications, GDML_Books,  (1967), pp. 121-127. http://gdmltest.u-ga.fr/item/700199/