Group By And String

Perhaps this is not the right description but I needed a tittle.

I have a query that consists out of multiple table.

The query contains 3 fields:
1. Course_ID
2. Part_ID
3. Page

I grouped the first 2 but here is the thing:
I want the contents of the page field to be displayed next to each other like this.

Query without grouping:

Course_ID Part_ID Page
1 | 2 | A
1 | 2 | B
1 | 2 | C
2 | 4 | S
2 | 2 | V

And it should be this:
Course_ID Part_ID Page
1 | 2 | A, B, C
2 | 4 | S
2 | 2 | V

How can I achieve this?