Different libraries in the Harvard University system have different rules for visiting scholars and guests.
Your first step is to use HOLLIS Plus to find out which library has the materials you need.
Once you’ve determined which library has the materials you need, you may contact the library or check its website to find out what its access policies are. Sometimes Harvard alumni or local scholars can apply for privileges. In some cases, fees are charged. If a letter of introduction is required for access, that can be provided to current NU faculty, staff and students in good standing. Contact the Research Help Desk on level 1 in Snell Library for assistance.