For decades, libraries have created a lot of mechanisms to organize the information. In National Technical Library (Narodni technicka knihovna - NTK) in Prague is such a mechanism the Polythematic Structured Subject Heading System (Polytematicky strukturovany heslar - PSH), primary intended to organize and search for documents by subject. This is no more solely the domain for librarians, but via internet there are a lots of users involved in it, too. Therefore, the PSH expands to catalogue and to make available also the web documents.

Besides PSH we will present other NTK services you may use without the need to visit the library - online.