Mayo Clinic: "Cold remedies: What works, what doesn't, what can't hurt," "I'm having trouble sleeping lately. Does this increase my chances of getting sick?" "How many hours of sleep are enough for good health?" "I seem to have chapped lips all winter. Is there anything I can do to prevent or treat chapped lips?"<br>PubMed Health: "Camphor/Eucalyptus Oil/Menthol (On the skin)."<br>Cleveland Clinic: "Common Cold."; AudioJungle