Asthma handbook
The asthma management handbooks is a comprehensive guide to asthma and living with asthma and it is free. It is very technical in places as it was designed for health care professionals. You can download it in PDF format or even print it out, all for free.
http://www.aaaai.org
This is a great website about allergies and their effects on asthma and asthma patients. It is definately worth a read. It can be a bit hard to navigate around the site, but the information is more then useful and it is free.
