This is the principal tool used for building up nanotechnological devices.

Federal funds are the Fed's principal tool in manipulating interest rates.

Then as now, terror is the principal tool of the totalitarian.

The restraint came from the Federal Reserve, whose principal tool for regulating the economy was interest rates.

Two of the principal symbolic tools always found in a Lodge are the square and compasses.

But their principal tool is now the Federal tax credit for corporations that invest in low-income housing.

The notes have been a principal tool in bailing out insolvent institutions.

Microbiological culture is a principal tool used to diagnose infectious disease.

Another principal tool in the diagnosis of infectious disease is microscopy.

The principal tool the organization provides is its web-based coordination tools.