DHHS:10.2345/0899-8205-43.1.73
DHHS:10.2345/0899-8205-47.4.343
DHHS:10.2345/0899-8205-47.s1.37
DHHS:10.2345/0899-8205-47.s1.42
DHHS:10.2345/0899-8205(2008)42[76:EASOEO]2.0.CO;2