Use Quick Search on the Library home page to find books that deal critically with Shakespeare's plays. First, select the "Advanced Search" function. On the first line, switch "Any Field" to "Subject." In the box to the right of that, leave "Contains" the way it is. On the far right (on the other side of the actual search box), select "Books and More (ISU Collections)." Then, for instance, you could do a search like Shakespeare Tempest and come up with a list of appropriate books.