Wion RK, Hill NL, DePasquale N, Mogle J, Whitaker EB. The relationship between subjective cognitive impairment and activity participation: a systematic review. Act Adapt Aging. 2020;44(3):225-45. doi: 10.1080/01924788.2019.1651188
Roberts J, Price J, Nelson LM, Burchinal M, Hennon E, Barnes B. Receptive vocabulary, expressive vocabulary, and speech production of boys with fragile X syndrome in comparison to boys with Down syndrome. Am J Ment Retard. 2007 May 1;112:177-93.