3Hyman, Herbert, "Interviewing in Social Research", Chicago : University of Chicago Press, ( 1954 ) , pp. 149 - 152.
4Raymond F & Robert Williams, "A Method for Measuring Error Due to Variance Among Interviewers", The Public Opinion Quarterly, ( 1956 ), p. 257 - 64.
5Hansen, Robert and S. Marks, "Influence of the Interviewer on the Accuracy of Survey Results'", Journal of the American Statistical Association, ( 1958 ) ,pp. 635 - 55.
6Hyman, H., Cobb, J., Feldman, J., and Stember, C., "Interviewing in Social Research", Chicago: University of Chicago Press, (1954),pp. 734 -61.
7Cannell & Fowler, "A note on interviewer effect in self-enumerative procedures", American Sociological Review, (1964) , p. 29 -38.
8Bailar Barbara A, "Some Sources of Error and Their Effect on Census Statistics", in Demography 13 (1976) ,pp. 273 - 86.
9Freeman J. & Edgar Butler, "Some sources of interviewer variance in surveys", Public Opinion Quarterly, ( 1976 ) , pp. 126 - 34.
