You can limit your search to publications from a single year by typing in a full four digit year, such as "2000", in one of the two year text input lines or limit your search to a range of years by typing in the upper and lower bounds in the two year text input lines.
The following entries will generate a pleasant error message.
Not entering the full four-digit year. Entering "96" or "04" will generate a pleasant error message.
Entering a nonnumeric character.
Entering a date older than the oldest date in the data base. The oldest reference in the data base was published in 1966.