K. N. Yugay, N. V. Blinov, and I. V. Shirokov, Flux quantization in stationary and nonstationary states in long Josephson junctions, Low Temp. Phys. 26, (2000) [Fiz. Nizk. Temp. 26, 1067-1072, (2000)] DOI: https://doi.org/10.1063/1.1330537.