Xin Du Lin Xin Ding Chen Wang Xie Xing Xu Shen wen Wang Li Chen Convergence analysis of gene expression programming based on maintaining elitist. 823-826 2009 GEC Summit http://doi.acm.org/10.1145/1543834.1543952 conf/gecco/2009 db/conf/gecco/gec2009.html#DuDXXWC09