HoTT/book — pull request #710 by araratm (2014-09-19 13:34:51+00:00)
Title: Updated some Punctuation problems.

In English Punctuation is important for your texts, because when I see a post which have a Punctuation problem, I will never read it, and most of the people will ignore it. It's the psychology of human.

You should put comma before which
it's utility instead of utlity