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HIRAYAMA, Naoki. Sentence Complexity in the Paston Letters: With Special Reference to the Letters by John Paston II. ERA. 2020. 36・37. 1・2. 47-61
HIRAYAMA, Naoki. Modal Auxiliaries of Obligation in the Paston Letters: With Special Reference to shall. Keisuisha、 The Pleasure of English Language and Literature. 2018. 47-62
HIRAYAMA, Naoki. Think and Trow in the Paston Letters. Kaitakusha;Studies in Middle;Modern English;Synchronic Aspects. 2017. 71-89
