Media type: E-Article Title: Advances in Databases and Information Systems: Paid Content a Way to Electronic Knowledge-Based Economy Contributor: Cellary, Wojciech imprint: Springer Berlin Heidelberg, 2010 Published in: Advances in Databases and Information Systems Language: Not determined DOI: 10.1007/978-3-642-15576-5_2 ISSN: 0302-9743; 1611-3349 Origination: Footnote: