Yoda is an immensely powerful Jedi who can control blue crackling Force lightning. It is a cruel weapon
of the Sith so he never normally sees it. But he knows that sometimes you must destroy your enemy
with their own weapons.

Star Wars: Mysteries of the Jedi

This scene changed all that, and we finally got to see Yoda fighting and using his full Jedi powers.

Star Wars Insider Magazine #122

He is about to destroy Dooku -- but, at the last moment, the clever Count escapes!

Star Wars: Battle in the Arena

However, when Master Yoda himself appeared, Dooku was driven back, barely escaping with his life.

Star Wars Fact File #046

If it hadn’t been for this manoeuvre, this humble hangar space could well have been where this
dastardly Sith Lord met his end.

Star Wars Fact File #101

Knowing he was bested and facing imminent defeat and death if the conflict continued [...]

Star Wars Fact File #065

Yoda jumps onto Dooku’s shoulders, and is about to drive the lightsaber into the top of the Count’s head. 
The end for you, Count, this is.

Star Wars: Attack of the Clones Script

When he is forced to choose between saving the lives of his compatriots or executing the final blow
in battle, Yoda chooses life over victory, allowing his enemy to escape. (Full Scan)

Star Wars: Yoda Unleashed

The count left Obi-Wan beaten and Anakin without his right-arm, and may have killed them
both if not for Yoda, who arrived and launched a whirlwind attack. Dooku barely escaped with his life.

Star Wars: The New Essential Chronology

Dooku battled the great Jedi Master to a standstill, and it was then that Yoda felt the presence
of the dark side in his former ally. Dooku escaped with his life, but did accomplish his main
goal - launching the great Clone Wars.

Star Wars: Galactic Battlegrounds Clone Campaigns

However, when Yoda appeared, Dooku was driven back, barely escaping with his life.

Star Wars Relaunched Fact Files #34