A method for supplying supplementary information related to printed books comprises the steps of: distributing a plurality of different printed books having respective content; supplying a common internet web access address together with each one of the plurality of different printed books; making a first web site accessible on the internet at the common address; firstly displaying at the first web site, in response to each internet access of the first web site, a first set of respective hyper links corresponding to each of the different printed books; and, secondly displaying at the first web site, in response to selection of any one of the hyper links on the first web page, a further and respective set of hyper links identifying further web sites having information relevant to and underlying the respective content of the printed book corresponding to the selected hyper link of the first web page. A programmed computer apparatus is a platform for the first web site and comprises a graphical user interface for generating the plurality of hyper links displayed for implementing the method.