Readers should cite both the Bio-protocol preprint and the original research article where this protocol was used:

Jiang, S, Sun, S and Qin, C(2021). Animal immunization and challenge studies. Bio-protocol Preprint. bio-protocol.org/prep811.
Gu, H., Chen, Q., Yang, G., He, L., Fan, H., Deng, Y., Wang, Y., Teng, Y., Zhao, Z., Cui, Y., Li, Y., Li, X., Li, J., Zhang, N., Yang, X., Chen, S., Guo, Y., Zhao, G., Wang, X., Luo, D., Wang, H., Yang, X., Li, Y., Han, G., He, Y., Zhou, X., Geng, S., Sheng, X., Jiang, S., Sun, S., Qin, C. and Zhou, Y.(2020). Adaptation of SARS-CoV-2 in BALB/c mice for testing vaccine efficacy . Science 369(6511). DOI: 10.1126/science.abc4730