Last update August 1, 2022

参考資料

 https://royalediting.com/the-usage-of-the-definite-article-rules-and-exceptions
 https://www.bbc.co.uk/worldservice/learningenglish/grammar/learnit/learnitv255.shtml
 https://www.quora.com/Why-did-some-languages-develop-a-definite-article-while-others-didnt?share=1
 https://en.wikipedia.org/wiki/Proto-Germanic_language
 https://en.m.wikibooks.org/wiki/Old_English/Articles
 https://en.wikipedia.org/wiki/Old_English_grammar
 https://en.wikipedia.org/wiki/Old_English
 https://en.wikipedia.org/wiki/Middle_English#Early_Middle_English
 https://www.etymonline.com/word/the
 https://en.m.wikibooks.org/wiki/Old_English/Articles
 http://www.lattice.cnrs.fr/IMG/pdf/Handbook.gramma.2010.pdf
 https://dspace.unive.it/bitstream/handle/10579/2584/815421-1165049.pdf;sequence=2
 Definiteness by Christopher Lyons (Cambridge Textbooks in Linguistics)