2. Migraine: Headache: Merck Manual Professional
Analgesics containing opioids, caffeine, or butalbital are helpful for infrequent, mild attacks but are prone to being overused, sometimes leading to rebound headache and daily headache syndrome. from the National Headache Foundation) Behavioral...
http://www.merck.com/mmpe/sec16/ch216/ch216d.html

3. Prevent Disease.com - New Agents Linked To 'Medication Overuse Headache' -- Prevent Disease.com
'Medication Overuse Headache' Medication overuse headache (MOH) "remains an important problem," but the drugs most likely associated with the overuse have changed dramatically in the past 15 years, according to headache specialists.
http://www.preventdisease.com/news/articles/062306_moh.shtml

4. Headache causes and treatment information from iVillage Total Health
Also known as an analgesic rebound headache, this type of headache results from overuse of pain medication. Primary headaches are often a tension headache, migraine or cluster headache. According to the American Council for Headache Education,...
http://yourtotalhealth.ivillage.com/headaches.html?pageNum=3