I know this won't be most people's cup of tea, but it's a pretty recent (2014) paper on academia and will interest anyone in early peninsula or archipelago technological development.
https://www.academia.edu/8065288/No_Rush_to_Judgment_The_Case_against_Japanese_as_an_Isolate?email_work_card=view-paper
(https://www.academia.edu/8065288/No_Rush_to_Judgment_The_Case_against_Japanese_as_an_Isolate?email_work_card=view-paper)