1. A method comprising: providing electronic data including a first electronic document, the first electronic document having a layout defining a rendered appearance, the first electronic document containing a plurality of references; receiving user input specifying a first selection operation that defines a first area of interest in the first electronic document based on the layout of the first electronic document; retrieving a second electronic document based on the first area of interest; and applying the first specified selection operation to define a second area of interest in the second electronic document.