The prime source of information about Middle-earth calendars is Appendix D to Prof. J. R. R. Tolkien’s translation of the Red Book of Westmarch. Thence have these quotations been extracted, in order to achieve a concordance among our reckoning of months and days on the one hand, and the five systems known to have been employed by the Eldar, the Hobbits and Men in the Third and Fourth Ages on the other hand.