1. Abraham, A. K. and Pihl, A.: 1981,TIBS 28, 106–107.
2. Baeza, I., Gariglio, P., Rangel, L. M., Chávez, P., Cervantes, L., Argüello, C., Wong, C., and Montañez, C.: 1987,Biochemistry 26, 6387–6392.
3. Baeza, I., Ibáñez, M., Santiago, J. C., Argüello, C., Wong, C., and Oró, J.: 1990,J. Mol. Evol. 31, 453–461.
4. Baeza, I., Ibáñez, M., Wong, C., Chávez, P., Gariglio, P., and Oró, J.: 1991,Origins of Life (submitted).
5. Bocian, E., Rosiek, O., and Ziembra-Aoltowski, B.: 1978,Bull. Acad. Pol. Sci. 26, 639–643.