2.  Colloquium, Department of Mathematics, Fordham University, April 24, 1978.

3.  Miniconference on Foliations, July 15-17, 1980, University of Notre Dame. Organized by Paul Schweitzer, S.J. of Pontificia Univ. Catholica, Rio de Janeiro.

4.  American Mathematical Society (88th Annual Meeting), Cincinnati, Ohio, January, 1982.

5.  Structure Transverse des Feuilletages, Feb. 17-19, 1982, Toulouse, France. Organized by Jean Pradines of Université Paul Sabatier, Toulouse.

6.  Geometry of Foliations, Nov. 12-13, 1982, East Lansing, Michigan. Special Session at American Mathematical Society meeting organized by Philippe Tondeur of University of Illinois.

7.  Colloquium, Department of Mathematics, Case Western Reserve University, January, 1983.

8.  American Mathematical Society (89th Annual Meeting), Denver, Colorado, January, 1983.

9.  Colloquium, Department of Mathematics, University of Notre Dame, Feb. 17, 1983.

10.  Seminar on Complex Analysis with Physical Applications, International Congress of Mathematicians, Aug. 16-24, 1983, Warsaw, Poland. Organized by Julian Lawrynowicz of the Polish Academy of Sciences (Lodz) and Leszek Wojtczak of the University of Lodz, Poland.

11.  Colloquium, Department of Mathematics, Washington University, Dec. 15, 1983.

12.  American Mathematical Society (90th Annual Meeting), Louisville, Kentucky, January, 1984.

13.  Colloquium, Department of Mathematics, Kansas State University, Feb. 9, 1984.

14.  Colloquium, Department of Mathematics, Lehigh University, March 23, 1984.

15.  Fifth International Colloquium on Differential Geometry, Sept. 24-28, 1984, Santiago de Compostela, Spain. Organized by Luis A. Cordero of University of Santiago de Compostela.

16.  Colloquium, Department of Mathematics, University of Alabama at Birmingham, Jan 31, 1985.

17.  U.S.-Spanish Workshop on Special Geometric Structures, May 30 - June 1, 1985, Valencia, Spain. Organized by Antonio Naveira of University of Valencia and David L. Johnson of Lehigh University.

18.  Second International Symposium on Differential Geometry, June 2-9, 1985, Peníscola Spain. Organized by the Department of Geometry and Topology of the Faculty of Mathematics of the University of Valencia, Spain.

19.  Differential Geometry, Nov. 1-2, 1985, Columbia, Missouri. Special Session at American Mathematical Society meeting organized by John Beem and Paul Ehrlich of University of Missouri, Columbia.

20.  Seminar on Differential Geometry, Department of Mathematics, University of Pennsylvania, Nov. 14, 1985.

21.  Seminar on Differential Geometry, Department of Mathematics, University of Maryland, Nov. 18, 1985.

22.  American Mathematical Society (93rd Annual Meeting), San Antonio, Texas, January, 1987.

23.  Fiftieth James E. Case Memorial Lecture, Saint Louis University, March 26, 1987.

24.  Transformation Groups in Geometry, Oct. 30 - Nov. 1, 1987, Lincoln, Nebraska. Special Session at American Mathematical Society meeting organized by Carolyn S. Gordon and Quo-Shin Chi of Washington University.

25.  Colloquium, Department of Mathematics and Statistics, Southern Illinois University at Edwardsville, Feb. 25, 1988.

26.  Colloquium, Department of Mathematics, State University of New York at Plattsburgh, Feb. 2, 1989.

27.  Lecture, Oglethorpe University, Feb. 16, 1989.

28.  Colloquium, Bard College, Feb. 24, 1989.

29.  Mathematical Association of America, Atlanta, Georgia, August 1-4, 1997.

30.  41^st Annual Georgia Mathematics Conference organized by the Georgia Council of Teachers of Mathematics, Eatonton, Georgia, October 19-21, 2000.

31.  40^th Annual Conference of the Association for General and Liberal Studies, Chicago, Illinois, November 2-4, 2000.