Your local parts store should be able to provide a belt routing diagram, if you provide year, make, model, and engine. They may be able to print this information for you to take home, or draw it out for you.
Some vehicles have this diagram printed on a decal on the radiator support, you may check there first.
If all else fails, you could try this link: http://www.gates.com/part_locator/
Enter your vehicle information, and it will show a listing for "serpentine belt", with a camera icon. Click the camera icon, and a window should open with the diagram you are looking for.
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