Prof. Wojciech Cellary participated in an annual conference of the International Group of Educational Publishers IGEP. The International Group of Educational Publishers is an association of the leading European publishing companies providing educational resources – both in print and digital forms. The IGEP 2010 conference was organized by Polish member of the association Young Digital Planet S.A. During the conference prof. Cellary gave an invited lecture "Paid Content a Way to Electronic Knowledge-Based Economy".