He also wrote and directed several episodes of the series.

He also directed episodes of the series during its run.

He directed 11 episodes of the series, more than any other individual.

He directed 15 episodes of the show from 1966 to 1967.

Later in 2000 he directed two episodes of Level 9.

The six 60-minute episodes were written and directed by others.

As of December 2008, he had directed 8 different episodes in the series, with more on the way.

He has directed multiple other episodes of the series throughout its run.

After leaving Doctors, he returned to direct and write several episodes.

During the run of the series, Nelson directed several episodes.