Perhaps you should try some spelling variations:
radiation instruments » radiation measurements
instruments theory » instruments history, instructors theory, instruments hedge
basics linear » basic linear, based linear, basics clear
basis linear » basic linear, bases linear, based linear
mass linear » bases linear, class linear, less linear

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: radiation instruments theory design ((((basis linear) OR (basics linear))) OR (mass linear))~.
• Adding a wildcard symbol may retrieve word variants: radiation instruments theory design ((((basis linear) or (basics linear))) or (mass linear))*.