Gorbalenya, A. E., Koonin, E. V., & Lai, M. M. (1991). Putative papain‐related thiol proteases of positive‐strand RNA viruses Identification of rubi‐ and aphthovirus proteases and delineation of a novel conserved domain associated with proteases of rubi‐, α‐ and coronaviruses. FEBS Lett.

Gorbalenya, Alexander E., Eugene V. Koonin, und Michael M.-C Lai. "Putative Papain‐related Thiol Proteases of Positive‐strand RNA Viruses Identification of Rubi‐ and Aphthovirus Proteases and Delineation of a Novel Conserved Domain Associated With Proteases of Rubi‐, α‐ and Coronaviruses." FEBS Lett 1991.

Gorbalenya, Alexander E., Eugene V. Koonin, und Michael M.-C Lai. "Putative Papain‐related Thiol Proteases of Positive‐strand RNA Viruses Identification of Rubi‐ and Aphthovirus Proteases and Delineation of a Novel Conserved Domain Associated With Proteases of Rubi‐, α‐ and Coronaviruses." FEBS Lett 1991.