Question regarding playground article

In the article 8-bit PCM audio using Arduino pulse-width modulation (PWM) Michael Smith included references to datasheet pages (as Use internal clock (datasheet p.160)).

Does anybody knows which datasheet precisely he means? Atmega32 doesn't seems to match ...

Thank you in advance.

This line gives a clue:

 * For Arduino with Atmega168 at 16 MHz.

Got it, thanks.