Article Measuring Expressed Emotion: An Evaluation of the Shortcuts
Kazarian SS, Malla AK, Cole JD, Baker B. Comparisons of two expressed emotion scales with the Camberwell Family Intervıew. J Clin Psychol. 1990;46:306–309. [PubMed]
Leff, J. P., & Vaughn, C. E. (1985). Expressed emotion in families. New York: Guilford Press.
The basic reference is Leff & Vaughn (1985), Expressed Emotion in Families, a book published by Guilford Press. The earliest source would be Brown & Rutter (1966) in the journal Human Relations. Your university library should be able to help with these. I agree with Stephen Messer that getting in touch with Jill Hooley is a good idea.