Medical and Biological Digital Library Research Lab, Department of Computer Science, University of Missouri, Columbia, MO 65211, USA. pinhao@diglib1.cecs.missouri.edu|Medical and Biological Digital Library Research Lab, Department of Computer Science, University of Missouri, Columbia, MO 65211, USA. pinhao@diglib1.cecs.missouri.edu|Medical and Biological Digital Library Research Lab, Department of Computer Science, University of Missouri, Columbia, MO 65211, USA. pinhao@diglib1.cecs.missouri.edu