I use dash to keep all of the reference material for libraries and programming languages I use stored locally. It has cut my searches down to almost nothing. IMO, it is better to use the reference material, because it forces you to understand the mechanisms involved and solve the problem yourself vs looking up a solution. This act helps imprint the knowledge into your long term memory. Of course, this is my anecdotal experience. As an aside, having the docs local is a godsend when working without internet or on a bad connection.