1. Ansari, H., & Babaii, E. (2003). Subliminal sexism in current EFL/ESL textbooks. The Asecondsian EFL Journal. http://asian-efl-journal.com/march03.sub1.pdf . Accessed 5 Dec 2017.
2. Australian Bureau of Statistics. (1996): Aspects of Literacy Assessed Skill Levels Australia 1996. Catalogue Number 4228.0. Canberra,Commonwealth of Australia. http://www.abs.gov.au/AUSSTATS/abs@.nsf/Previousproducts/4228.0Main%20Features11996?opendocument&tabname=Summary&prodno=4228.0&issue=1996&num=&view= . Accessed 12 Nov 2017.
3. Australian Bureau of Statistics. (1997): Australians’ Literacy Skills Put to the Tests. http://www.abs.gov.au/AUSSTATS/abs@.nsf/Previousproducts/4228.0Media%20Release11996?opendocument&tabname=Summary&prodno=4228.0&issue=1996&num=&view= . Accessed 12 Nov 2017.
4. Babbie, E. R. (1990). Survey research methods Wadsworth Pub (pp. 78–82). Belmont: Wadsworth Publishing.
5. Bialystok, E. (1997). The structure of age: In search of barriers to second language acquisition. Second Language Research, 13(2), 116–137.