American Association for Home Care American Association for Retired Persons American Association for Respiratory Care American Cancer Society American Heart Association American Lung Association Bon Secours of Hampton Roads Cancer Symptoms CHEST Journal Heart Information Medical Dictionary National Heart, Lung and Blood Institute PERF (Pulmonary Education and Research Foundation) Portable Oxygen (A users perspective) PulmonologyLinx Quit Smoking Support (CDC) The Respiratory System Riverside On-line Sentara Hospital Virginia Oncology Associates