Publication date

I reformatted the date of publication field in the database, so the list of books could be sorted by date. For books I did not know the exact day, but new the month I used the first day of the month. For books that I knew only the year of publication I used January 1 f the year. I am aware that this kind of usage is incorrect, but the database format required me to come with a specific date and this seemed the most consistent.