Haining Lu Dawu Gu Chongying Jin Yinqi Tang Reducing extra storage in searchable symmetric encryption scheme. 255-262 2012 CloudCom https://doi.org/10.1109/CloudCom.2012.6427599 https://doi.ieeecomputersociety.org/10.1109/CloudCom.2012.6427599 conf/cloudcom/2012 db/conf/cloudcom/cloudcom2012.html#LuGJT12