Zhang, K., X. Xia, S. Deng, Y. Zhong, D. Xie, G. Pan, J. Wu, Q. Liu, X. Wang, and J. Tu. “Nitrogen-Doped Sponge Ni Fibers As Highly Efficient Electrocatalysts for Oxygen Evolution Reaction”. Nano-Micro Letters, vol. 11, Mar. 2019, p. 21, doi:10.1007/s40820-019-0253-5.