Perhaps you should try some spelling variations:
national laboratories » national laboratory
federal laboratories » chemical laboratories, research laboratories, virtual laboratories
medical laboratory » clinical laboratory

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: ((((national laboratories) OR (medical laboratory))) OR (federal laboratories)).
• Adding a wildcard symbol may retrieve word variants: ((((national laboratories) or (medical laboratory))) or (federal laboratories))*.