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Beatty, P.; Herrmann, D.; Puskar, C.; Kerwin, J. (July 1998). ""Don't know" responses in surveys: is what I know what you want to know and do I want you to know it?". Memory (Hove, England). 6 (4): 407–426. doi:10.1080/741942605. ISSN0965-8211. PMID9829099.
Streiner, D. L. (2003). "Starting at the beginning: An introduction to coefficient alpha and internal consistency". Journal of Personality Assessment. 80 (1): 99–103. doi:10.1207/S15327752JPA8001_18. PMID12584072. S2CID3679277.
Beatty, P.; Herrmann, D.; Puskar, C.; Kerwin, J. (July 1998). ""Don't know" responses in surveys: is what I know what you want to know and do I want you to know it?". Memory (Hove, England). 6 (4): 407–426. doi:10.1080/741942605. ISSN0965-8211. PMID9829099.
Streiner, D. L. (2003). "Starting at the beginning: An introduction to coefficient alpha and internal consistency". Journal of Personality Assessment. 80 (1): 99–103. doi:10.1207/S15327752JPA8001_18. PMID12584072. S2CID3679277.
Beatty, P.; Herrmann, D.; Puskar, C.; Kerwin, J. (July 1998). ""Don't know" responses in surveys: is what I know what you want to know and do I want you to know it?". Memory (Hove, England). 6 (4): 407–426. doi:10.1080/741942605. ISSN0965-8211. PMID9829099.