文献检索中的跟踪法指的是 （ ）

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SQL Error: select id,body,options from ***_enewstiku where sourceid='25992' and id < 2181439 and id<>'2181439' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='25992' and id > 2181439 and id<>'2181439' order by id asc limit 5