E Librarian Service : User Friendly Semantic Search in Digital Libraries This book introduces a new approach in designing E Librarian Services. Such a system is able to retrieve multimedia resources from a digital library in a more efficient way than by browsing through an index or by using a simple keyword search. It combines recent advances in multimedia information retrieval with aspects of human machine interfaces. The user can enter his question in natural language. The premise is that more pertinent results would be retrieved if the search engine understood the sense of the users query. The returned results are then logical consequences of an inference rather than of keyword matchings. An E Librarian Service simulates a human librarian. Hence it does not return the answer to the users question but it retrieves the most pertinent document(s) in which the user finds the answer to his question. Also an E Librarian Service always proposes a solution to the user even if the system concludes that there is no exhaustive answer.