I am researching the patentability of an invention related to software documentation tools that auto-document a software application. Can anyone guide me as to the best way of going about researching prior patents in this field of invention? I have spent a day on the PTO website trying to figure out the appropriate classification for such an invention but the patents I am finding do not seem to be relevant (CCL/715/500 - PRESENTATION PROCESSING OF DOCUMENT). Is there a time/cost effective way of doing this?