1. Headache causes and treatment information from iVillage Total Health
Primary headaches are often a tension headache, migraine or cluster headache. According to the American Council for Headache Education, more than 90 percent of headaches are primary headaches. Commonly referred to as an ice cream headache, this...
http://yourtotalhealth.ivillage.com/headaches.html?pageNum=3

2. Clinical Practice Guidelines for Nurses in Primary Care -- Health Canada - Sant Canada
When a client first presents to the clinic with headache, the following points in the history must be obtained to assist in differentiating the type of headache. multiple sclerosis, Parkinson's disease) Migraine headaches.
http://www.hc-sc.gc.ca/fnih-spni/pubs/nursing-infirm/2000_clin-guide/chap_08a_e...

3. Headache Disorders: Currents: UI Health Care -- Ui Health Care Home
3.1 Cluster headache 3.1.1 Cluster headache periodicity undetermined 3.1.2 Episodic cluster headache 3.1.3 Chronic cluster headache 3.2 Chronic paroxysmal hemicrania 3.3 Cluster headache-like disorder not fulfilling the above criteria 4.
http://www.uihealthcare.com/news/currents/vol2issue3/3headache.html