1. Stability and synthesis of two-dimensional recursive filters
2. M. Ahmadi, A. G. Constantinides, and R. A. King, "Design technique for a class of stable twodimensional recursive digital filters," inProc. 1976 IEEE Int. Conf. Acoust., Speech,Signal Processing, 1976, pp.145-147.
3. On 2-variable reactance functions for 2-dimensional recursive filter design
4. Digital Filtering in One and Two Dimensions