Minh Bao, T. and Cong Tuan, T. 2016. Query Optimization in Object Oriented Databases Based on SD-Tree and n-ary Tree. EAI Endorsed Transactions on Context-aware Systems and Applications. 3, 8 (Mar. 2016), e2. DOI:https://doi.org/10.4108/eai.9-3-2016.151114.