JOURNAL OF DIFFERENTIAL EQUATIONS, vol. 81, no. 2, page. 255 - 274, 1989-10
JOURNAL OF DYNAMICS AND DIFFERENTIAL EQUATIONS, vol. 1, no. 3, page. 269 - 298, 1989-07
COMMUNICATIONS IN MATHEMATICAL PHYSICS, vol. 121, no. 1, page. 11 - 33, 1989-03
COMMUNICATIONS IN PARTIAL DIFFERENTIAL EQUATIONS, vol. 14, no. 6, page. 833 - 834, 1989-01