Citation, Documentation of Sources

Q. Dear CMOS Staff, I am citing a periodical. In 1918 it started as a weekly and had a month/day date as well as an issue number. In 1920, the periodical became a quarterly, with a year and issue number (but no date). I am citing one from 1918 and one from 1920. Should I cite the 1918 with the date or be consistent with the 1920 without the date?

A. Give all the information you have. Consistency is counterproductive if it requires hiding information from the reader. If it makes you twitch to have no weekly date for 1920, put “[n.d.]” where the month and day would go.