From: <[log in to unmask]> Date: Fri, 14 Sep 2012 09:58:10 +0000 I responded to Chen's first article (for those of you who subscribe to Serials Review: http://dx.doi.org/10.1016/j.serrev.2011.01.003). My point is: Google Scholar is an addition to subscription-based databases, certainly not a replacement. Google Scholar's interface has several disadvantages: 1. Google cannot handle complexity very well. Usually, a literature search question is complex. Such a question will consist of a combination of semantic components, and these components can be weighed as well. A complex question can yield hundreds or sometimes thousands of relevant references in subscription-based databases. Because Google Scholar cannot handle complexity, vocabulary control or term weighing in a proper way, results will lack recall. 2. Google's excellent coverage diminishes precision in search results. A simple search in Google Scholar, say "rheumatoid arthritis," will result in some very relevant references, but also in tens of thousands of items which are not relevant at all. So results will lack precision. 3. Google Scholar has no instruments to control semantics. For example, Google Scholar cannot distinguish between depression (mental disease) or depression (physiologic phenomenon). It also cannot distinguish migration (geographic mobility) and migration (cellular biology). 4. Google Scholar's gigantic coverage can be misleading. Now and again, for very specific simple questions, recall of Google Scholar can be incomplete. Recently, I searched for a very specific text string: Health-F2-2008-223404. Google Scholar will yield 22 references, whereas in all combined subscription based databases, a total of 64 references were found. Dedicated databases are still very valuable, not only in science but also in patient care and education. Cordially, Jan W. Schoones Walaeus Library LUMC, Leiden, The Netherlands http://www.lumc.nl/JanWSchoones