Frequency degenerate and non-degenerate nonlinear regimes for semi-linear photorefractive oscillatorM. Grapinet, P. Mathey, H. R. Jauslin, B. Sturman, D. Rytz and S. OdoulovEur. Phys. J. D, 41 2 (2007) 363-369DOI: https://doi.org/10.1140/epjd/e2006-00223-y