(1) Y. C. Cheng, 1976, "Ground-State Lattice Vacancies and Bose-Einstein Condensation in a Quantum Crystal", *Phys. Rev. ***B14 **, 1946.

(2) Y. C. Cheng, 1981, "Excitation Spectrum of a Supersolid", *Phys. Rev. ***B23 **, 157.

(3) Y. C. Cheng and J. S. Yang, 1990, "Enhancement of the Van Der Waals Energy Between an Atom and a Cylindrical Surface: Application to the Edges of Stepped Surfaces", *Phys. Rev. ***B41 **, 1196.

(4) C. K. Yang, Y. C. Cheng, and S. Y. Wu, 1994, "Electronic Structure Calculation for a Stepped Cu(110) Surface by Using a Real Space Approach", Phys. Lett. **A188 **, 68.

(5) Y. H. Shiau, Y. C. Cheng, and C. K. Hu, 1998, “Stochastic Postponement of the Domain Transitions and Destabilization of Current in the Gunn Diode *” *, *Phys. Rev. ***E57 **, R1227 (Rapid Communications).