I mean that money is the indispensable source both of motivation and of performance measurement.

It has been updated twice since its first publication in the 1990s, and has become an indispensable source for virtually all subjects concerning the area.

From 1400 on it is an indispensable source of Austrian history (ed.

In the days before the Internet and music blogs, it was an indispensable source for underground music.

Written shortly after a decade of civil conflict, it is an indispensable source for understanding politics and society in nineteenth-century Chile.

Worship is the heart of parish life, "the primary and indispensable source from which the faithful are to derive the true Christian spirit."

It is also an indispensable source for those who conduct research on Chinese economy.

Peppiatt has also been able to draw on what will from now on be an indispensable biographical source.

The book is now considered an indispensable source of information on the Lincoln White House.

Electricity is an indispensable source of energy which we take for granted in our everyday lives.