Comma after introductory phrase

[Karsten82]

Hi,

I am confused about whether there is a comma after introductory phrases like the following two:

"In chapter 123, we discussed...."

"In the following, we will further explain ..."

On the web, I found roughly a 50:50 distribution of cases with comma and without. What is correct? My guess: there must be a comma after these introductory phrases, right?

Thank you for your help!

[JohnParis]

I would use commas if I were writing those phrases.