@article{articleab5ed86a,
title   = {On harmonic and subharmonic solutions of nonlinear second order equations: symmetry and bifurcation},
author = {Furkotter, Monica and Rodrigues, Hildebrando Munhoz},
year = {1990},
doi = {10.1080/00036819008839942},
journal   = {Applicable Analysis: An International Journal}
}