Page 597: Description of "move_backward" from <algorithm> has typos.

[WraithGlade]

From the following text:

The result is that the elements of detector1 are in a moved from state ➎ ➏ and the elements of detector2 are moved into ➐ ➑.

The typos are:

(1) detector1 --> detectors1

(2) detector2 --> detectors2

[JLospinoso]

Thanks, @WraithGlade!