1. Azuma, N. (2021). How to Improve and Evaluate English Speaking Ability through Impromptu Speech and Dialog. KELT, 36, 3-20.
2. Baddeley, A. (2000). The Episodic Buffer: A new component of working memory?. Trends in Cognitive Sciences, 4, 417-423.
3. Baddeley, A.D. (2002). Is Working Memory Still Working? European Psychologist, 7, 2, 85-97.
4. Brody, M. (1998). Speaking Your Way to the Top: Making powerful business presentations. Boston: Allyn and Bacon.
5. Cowan, N. (2000). The Magical Number 4 in Short-term Memory: A reconsideration of mental storage capacity. Behavioral and Brain Sciences, 24, 87-185.
6. Educational Testing Service (ETS). (2021a). TOEFL iBT Test and Score Data Summary 2020: January-December 2020 test data. Retrieved from https://origin-www.ets.org/s/toefl/pdf/toefl_tsds_data_2020.pdf
7. Educational Testing Service (ETS). (2021b).Performance Descriptors for the TOEFL iBT Test. Retrieved from https://www.ets.org/s/toefl/pdf/pd-toefl-ibt.pdf
8. Hertz, B., Kerkhof, P., & Woerkum, C.V. (2016). PowerPoint Slides as Speaking Notes: The influence of speaking anxiety on the use of text on slides. Business and Professional Communication Quarterly, 1-12.
9. Higa, Y. (2017). Interaction to Producation wo Jushi shita Speaking Shido no Kufu: ICT wo Katsuyo shita Gengokatsudo no Kasseika wo Toshite. Okinawakenritsu Sogokyoiku Center Kokichokikenshuin Kenkyu Shuroku, 61, 1-11.
10. Henderson, D. (1982). Impromptu Speaking as a Tool to Improve Non-native Speakers’ Fluency in English. JALT Journal, 4, 75-87.
11. Horwitz, E. K., Horwitz, M. B., & Cope, J. (1986). Foreign Language Classroom Anxiety. The Modern Language Journal, 70 (2), 125-132.
12. Izumi, E. & Kadota, S. (2016). Eigo Speaking Shido Handbook. Tokyo: Taishukan.
13. Kadota, S. (2007). Shadowing to Ondoku no Kagaku. Tokyo: Cosmopier.
14. McLaughlin, B. (1987). Theories of Second-language Learning. London: Edward Arnold.
15. Miller, G.A. (1956). The Magical Number Seven, Plus or Minus Two: Some limits on our capacity for processing information. Psychological Review, 63, 81-97.
16. Ministry of Education, Sports, Science and Technology (MEXT). (2017). The Junior High School Course of Study (Notified 2017) Commentary: Foreign Languages. Retrieved from https://www.mext.go.jp/component/a_menu/education/micro_detail/__icsFiles/afieldfile/2019/03/18/1387018_010.pdf
17. Nomura, K. (2011). Macrotask ni Motozuku Public Speaking Noryoku no Ikusei. Kobegaidai Ronso, 62 (2), 117-136.
18. Repovs, G. & Baddeley, A. (2006). The Multi-component Model of Working Memory: Explorations in experimental cognitive psychology. Neuroscience, 139, 5-21.
19. Tamonob, A. H. (2015). Students’ Fear towards Impromptu Speech Activities in Speaking Class at the English Department of Satya Wacana Christian University. Thesis submitted at Tatya Wacana Christian University.
20. Tanaka, H. (2013). The KJ Method Quick Manual. Gaikokugo Kyoiku Media Gakkai Kansaishibu Methodology Kenkyu Bukai Hokoku Ronshu 2012, 102-106.