GERARD JENNHWA CHANG2018-09-102018-09-102003http://www.scopus.com/inward/record.url?eid=2-s2.0-21144456361&partnerID=MN8TOARShttp://scholars.lib.ntu.edu.tw/handle/123456789/301300The L(2, 1)-labeling problem on ditreesjournal article