Is there a place to report issues?

In section 2.9.1 Quaternions, 4th paragraph reads as if it's missing an equation for the second representation of a quaternion:

  A quaternion can be represented as a quadruple [EQ present] or as [EQ missing] , where is an imaginary 3-vector and  is the real part. We will use both representations interchangeably in this section. 

This is what it looks like for me:

https://imgur.com/a/3Mfanma