1. School of Information, Yunnan University, Kunming, Yunnan, China
2. School of Information (Key Laboratory of Educational Informatization for Nationalities, Ministry of Education), Yunnan Normal University, Kunming, Yunnan, China
3. Key Laboratory of Educational Informatization for Nationalities, Ministry of Education, Yunnan Normal University, Kunming, Yunnan, China
4. National Pilot School of Software, Yunnan University, Kunming, Yunnan, China