Shaffer Jeffrey Duane. An Improved Measure of Grammatical Complexity (A First Step in More Accurately Assessing the Readability of a Text). The Journal of Shizuoka University Education. 2022. 2022. 18
Shaffer Jeffrey Duane. The Potential Use of the "Lord of the Rings" Book Series for Incidental Vocabulary Acquisition. The Journal of Shizuoka University Education. 2020. 2020. 16
Shaffer Jeffrey Duane. The Potential Use of the Harry Potter Book Series for Incidental Vocabulary Acquisition. The Journal of Shizuoka University Education. 2018. 2018. 14. 67-82
Shaffer, J.D. Enjoying English Through Writing: Editing. 英語教育. 2017. 65. 13. 64-65
Shaffer, J.D. Enjoying English Through Writing: Show, Don't Tell. 英語教育. 2017. 65. 12. 64-65
Shaffer, J.D. Varying degrees of contextual narrowness in narrow reading and its potential impact on vocabulary acquisition. Temple University Japan Studies in Applied Linguistics: Teaching Vocabulary to Second Language Learners. 2004. 41. 95-104
Shaffer, J.D. Improving test efficiency through calculated item reduction. Temple University Japan Studies in Applied Linguistics: Language Assessment. 2004. 36. 61-70
Shaffer, J.D. The Academic Word List and Oral Academic Discourse. Temple University Japan Studies in Applied Linguistics: Teaching Vocabulary to Second Language Learners. 2004. 41. 105-113