@article{article33213973,
title   = {Oscillating and periodic solutions of equations of type 'X DOIS PONTOS' + x + 'X PONTO' 'SOMATORIA SOB N' 'SOBRE IMAGINARIO = 1' 'F IND. IMAGINARIO' (x) 'X PONTO POT. DELTA IMAGINARIO' + g (x) =0},
author = {Guidorizzi, Hamilton L.},
year = {1993},
doi = {10.1006/jmaa.1993.1218},
journal   = {Journal of Mathematical Analysis and Its Applications}
}