Two high potential cases of SNFs in low frequency range for γ Dor stars. Left panels: LSP in the range where the majority of frequencies are detected. A close-up view of the SNF is zoomed inside. The red vertical arrow locates the SNF. Right panels: Sliding LSP, centered on the SNF, displays a periodic pattern of frequency modulation, which is compared with the theoretical variation of the SNF (solid curve) and a phase (π/2) shifted result (dashed curve).