Page 480
Question Mark
A question mark is used after an interrogative sentence or to show doubt about the correctness of a fact or figure.

480.1 Direct Question
A question mark is used at the end of a direct question (an interrogative sentence).
Have you ever heard of a sunken galleon code-named the Black Swan by those who discovered it?
480.2 Indirect Question
No question mark is used after an indirect question.
Mr. Dehnke asked if anyone was interested in doing a report on the ship and its treasure.
He also asked if we knew the significance of the name Black Swan.