Naruhito graduated from Gakushuin University in March 1982 with a Bachelor of Letters degree in History.[18] In July of the next year he entered a three-month intensive English course before entering Merton College, Oxford University, in the United Kingdom,[19] where he would study until 1986. Naruhito would not, however, submit his thesis A Study of Navigation and Traffic on the Upper Thames in the 18th Century until 1989.[20] He later revisited these years in his book, The Thames and I – a Memoir of Two Years at Oxford.