1. Asaro, P. et al. Geol. Soc. Am. Spec. Pap. 190, 517–528 (1982).
2. Alekseev, A. S. et al. in Abstr. 14th Lunar planet. Sci. Conf. 3–4 (NASA, 1983).
3. Zhang, J. et al. Acta Petrol Miner. Analyt. 2, 81–86 (1983).
4. Sun, Y. Y. et al. in Development in Geoscience (ed. Tu Guangzhi) 235–245 (Academia Sinica, Beijing, 1984).
5. Li, Z. et al. An excursion guide to the Permian–Triassic Boundary section, Guangyuan, Sichuan Province (in the press).