- Sequence heterogeneity of TT virus and closely related viruses. Khudyakov, Y.E., Cong, M.E., Nichols, B., Reed, D., Dou, X.G., Viazov, S.O., Chang, J., Fried, M.W., Williams, I., Bower, W., Lambert, S., Purdy, M., Roggendorf, M., Fields, H.A. J. Virol. (2000)