Despite the fact that many Digital Libraries (DLs) are available on the Internet, users cannot effectively use them because of inadequate functionality, deficient visualization and insufficient integration of different DLs. As part of the DAFFODIL project we develop a user-oriented access system for DLs which overcomes these drawbacks. A major focus of the prototype concerns the implementation of search stratagems that exhaust the data structures stored in federated bibliographic DLs. The paper introduces stratagems taking into account information on the (social) status of scientific actors in author networks using network analysis methods. To make the propagation and analysis of actor networks more efficient an optimization strategy called main path analysis is employed.