@article{GDZPPN002362465,
title = {On the Location of Zeros of Solutions of f'' + A(z)f = 0 where A(z) is Entire.},
journal = {Mathematica Scandinavica},
volume = {74},
year = {1994},
pages = {293-312},
zbl = {0827.34003},
url = {http://dml.mathdoc.fr/item/GDZPPN002362465}
}
Wu, Shengjian. On the Location of Zeros of Solutions of f'' + A(z)f = 0 where A(z) is Entire.. Mathematica Scandinavica, Tome 74 (1994) pp. 293-312. http://gdmltest.u-ga.fr/item/GDZPPN002362465/