Hong J, Novick D, Montgomery W, Aguado J, Dueñas H, Peng X, Haro JM. Should unexplained painful physical symptoms be considered within the spectrum of depressive symptoms? Clin Pract Epidemiol Ment Health. 2015 Mar 31;11:130-9. doi: 10.2174/1745017901511010130
Gfroerer J, Lessler J, Parsley (Edwards) T. Studies of nonresponse and measurement error in the national household survey on drug abuse. Nida Res Monogr. 1997;167:273-95.