Formula for determining if two date columns fall within specific date range

Let's say I have thousands of employees, but I need to determine who worked for me during a particular date range, and all I have to go on is their start date in one column and their end date in another column.

If:

A1 contains beginning date of employment
B1 contains ending date of employment
C1 contains specified beginning date (criteria)
D1 contains specified ending date (criteria)

is there a formula to help make this determination?