"Mathematics : Motivation, Creativity and Joy! (the Conference in honor of Prof. Heisook Lee), 2014-02-14
International Symposium on New Frontiers in Scientific Innovation, 2014-07-08
MATHEMATISCHE ZEITSCHRIFT, vol. 212, no. 1, page. 175 - 192, 1993-02
Springer Monographs in Mathematics, page. 253 - 273, 2020-10
ASIAN JOURNAL OF MATHEMATICS, vol. 1, no. 1, page. 96, 1997-03