Tatyana Ryutov Li Zhou B. Clifford Neuman Noria Foukia Travis Leithead Kent E. Seamons Adaptive trust negotiation and access control for grids. 55-62 2005 conf/grid/2005 GRID http://dx.doi.org/10.1109/GRID.2005.1542724 db/conf/grid/grid2005.html#RyutovZNFLS05