Dmitri E. Kirichenko and Igor V. Vernik, “High Quality On-Chip Long Annular Josephson Junction Clock Source for Digital Superconducting Electronics,” IEEE Trans. Appl. Supercond., 15, 296-299, June 2005
Igor V. Vernik and Deepnarayan Gupta, “Two-phase 50 GHz on-chip long Josephson junction clock source,” IEEE Trans. Appl. Supercond. 13, 587-590, June 2003
D. Gupta and Y. Zhang, “On-chip clock technology for ultrafast digital superconducting electronics,” Appl. Phys. Lett., vol. 76, p. 3819, (2000).