Search is free for noncommercial use. For the commercial use the rules are described in the footer of your browser. It is a great tool, even for users who have basic problems with the operation of computer hardware. The database, like all, has the largest number of articles in English. Unique advantage of this database (in contrast to many others) is that you can make any filtration of the desired criteria. This is particularly useful in the search of the scientific literature. There is an ability to obtain information related to the searched articles in the database, which apparently did not relate to the original. Based on the context and the keywords.