Bryant, R., Chern, S. S., & Griffiths, P. A. (1982). Exterior Differential Systems. In S. S. Chern & W. T. Wu (Eds.), Proceedings of the 1980 Beijing Symposium on Differential Geometry and Differential Equations (Beijing, 1980) (Vol. 1, pp. 219–338). Beijing, PRC; New York, NY: Science Press; Gordon & Breach Science Publishers.

Bryant, R., S. S. Chern, and P. A. Griffiths. “Exterior Differential Systems.” In Proceedings of the 1980 Beijing Symposium on Differential Geometry and Differential Equations (Beijing, 1980), edited by S. S. Chern and W. T. Wu, 1:219–338. Beijing, PRC; New York, NY: Science Press; Gordon & Breach Science Publishers, 1982.

Bryant R, Chern SS, Griffiths PA. Exterior Differential Systems. In: Chern SS, Wu WT, editors. Proceedings of the 1980 Beijing Symposium on Differential Geometry and Differential Equations (Beijing, 1980). Beijing, PRC; New York, NY: Science Press; Gordon & Breach Science Publishers; 1982. p. 219–338.

Bryant, R., et al. “Exterior Differential Systems.” Proceedings of the 1980 Beijing Symposium on Differential Geometry and Differential Equations (Beijing, 1980), edited by S. S. Chern and W. T. Wu, vol. 1, Science Press; Gordon & Breach Science Publishers, 1982, pp. 219–338.

Bryant R, Chern SS, Griffiths PA. Exterior Differential Systems. In: Chern SS, Wu WT, editors. Proceedings of the 1980 Beijing Symposium on Differential Geometry and Differential Equations (Beijing, 1980). Beijing, PRC; New York, NY: Science Press; Gordon & Breach Science Publishers; 1982. p. 219–338.