Wizard's Spellbook when casting?

[Randomocity132]

A wizard needs his spellbook to prepare spells. Does he need it in hand to cast them? I had always thought he did, but I can't see the specifics on whether or not he needs it when casting a spell.

[Diarmuid]

Nope. He needs to have at least 1 hand free for somatic components and being able to access any necessary material components.

[Kraken]

It needn't be on hand, and in fact keeping it well stowed is prudent.