From my extensive observation of the rich, I find there are many of them whose lives have gone very wrong.

During his extensive observations, he catalogued more than 800 double stars and 2,500 nebulae.

Many of the members had no formal education, but came by their expertise through extensive direct observation.

And the tycoon confirmed as much to be true from his own extensive observations.

Remote sensing is a relatively new concept and so extensive historical observations are unavailable.

Gilbert based his findings on extensive observation and practical experiments.

After extensive observation and research, she has become able to recognize elephants by their voices.

This fact has been put in the clearest light by extensive observations made upon animals.

"Based on my extensive observation of him, you mean?"

My extensive observations only lasted for a few minutes, during which I did most of the talking.