When skimming through a long mathematical paper (in pdf format), I often find a mathematical symbol (often in greek and with subscripts/superscripts) that was defined previously somewhere else within the paper. Of course, it's not always easy to find where the parameter was defined, so I resort to using the FIND tool. However, simply copy and pasting the symbol to the FIND tool doesn't seem to work well, since the symbol cannot be copied exactly.
Is there a better way to perform an automated search a PDF document for a particular mathematical symbol if I don't have the original latex file? Especially ones with subscripts and superscripts?