Zi Huang Heng Tao Shen Jie Shao Xiaofang Zhou Bin Cui Bounded coordinate system indexing for real-time video clip search. 2009 27 ACM Trans. Inf. Syst. 3 http://doi.acm.org/10.1145/1508850.1508855 db/journals/tois/tois27.html#HuangSSZC09