Everitt, William Norrie; Giertz, Magnus: On limit-point and separation criteria for linear differential expressions.
(English).
In:
Ráb, Miloš
and Vosmanský, Jaromír (eds.): Proceedings of Equadiff III.
3rd Czechoslovak Conference on Differential Equations and Their Applications. Brno, Czechoslovakia, August 28 - September 1, 1972.
Univ. J. E. Purkyně - Přírodovědecká fakulta, Brno, 1973.
pp. 31-42