1. Balan, R., Casazza, P., Heil, C., Landau, Z.: Density, overcompleteness, and localization of frames. II. Gabor systems. J. Fourier Anal. Appl. 12, 309–344 (2006)
2. Casazza, P.G., Christensen, O.: Gabor frames over irregular lattices. Adv. Comput. Math. 18, 329–344 (2003)
3. Christensen, O., Deng, B., Heil, C.: Density of Gabor frames. Appl. Comput. Harmon. Anal. 7, 292–304 (1999)
4. Christensen, O., Favier, S., Zó, F.: Irregular wavelet frames and Gabor frames. Approx. Theory Appl. (N.S.) 17, 90–101 (2001)
5. Feichtinger, H.G., Sun, W.: Sufficient conditions for irregular Gabor frames. Adv. Comput. Math. 26, 403–430 (2007)