1. Professor Y.C. Wong — Four decades as my mentor, colleague and friend SIU Man Keung Department of Mathematics University of Hong Kong

2. October 23, 1998 HKU

4. October 1963 HKU

5. UNIVERSITY OF HONG KONG DEPARTMENT OF MATHEMATICS I. Five Main Steps in Studying Mathematics 1.Preparing before the lecture. 2.Attending the lecture. 3.Reviewing after the lecture. 4.Doing exercises. 5.Looking back. 1/10/YCW/1w/63

7. Two theorems in the first year lectures :

8. American Mathematical Monthly, 48 (1941), 530-535.

9. Y.C. Wong, Some properties of the triangle, American Mathematical Monthly, 48 (1941), 530-535. Y.C. Wong, Some extensions of the Douglas- Neumann theorem for concentric polygons, American Mathematical Monthly, 75 (1968), 470-482. S.B. Gray, Generalizing the Petr-Douglas- Neumann theorem on N-gons, American Mathematical Monthly, 110 (2003), 210-227.

13. June 1970 New York

14. March 1967 New York

15. July 1970 Peak of Otters, Virginia

16. June 1972 New York

18. Thank you very much indeed for your most interesting and informative letter of October 11, 1969. ……… I appreciate very much your taking the trouble to write us such a long letter. It must have taken you two or three hours of your valuable time. Perhaps you should arrange among yourselves to take turn to do this. Letter from Professor Y.C. Wong October 17, 1969.

20. You said you are a beginning teacher, but what you said in that letter as well as an earlier one about what a teacher should do is very similar to what I learn from my long experience as a teacher. If you keep on using your imagination and experimenting in this way, you may some day become an outstanding teacher of mathematics. Letter from Professor Y.C. Wong November 29, 1972.

21. July 1982 Vancouver

22. August 1978 Helsinki

23. 欣逢黃教授九十華誕 謹祝教授健康長壽， 永遠幸福。 莫錦屏 2003.5.20

25. December 1965 HKU

26. December 1965 HKU

27. December 1965 HKU

29. …… Therefore thank you again, Professor Wong, and best wishes. Your six decades as mathematician and educator have touched on many lives, and mine is one of them. Lai Tze-Leung May 21, 2003 September 1968 New York

30. Happy Birthday and Many Happy Returns, Professor Wong! Best Wishes to You, Professor Wong and Mrs. Wong!