After 1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.cxd5 Nxd5 5.Nf3 Bg7 6.Qb3, Black will decide for White where the c1-bishop will deploy. (Diagram)
Keene & Jacobs offer the illustrative game, Tisdall - Jansa, 1983, featuring 7.Bg5, and analyze Schiller's recommendation of 7.Bf4 in the notes. To my eyes, 7.Bf4 seems more flexible since it helps control both e5 and c7. I will edit this post as I find more resources on this line.
I am a big fan of GM author Jacob Aagaard, yet his Starting Out: The Grunfeld is harshly dismissive of this variation, which he writes off in a single sentence. Yet, it's not clear-- to me anyway-- why the power of the Russian and Exchange systems should be entirely lost on this hybrid that combines features of the two. In any case, this fairly straightforward variation was the frontline choice for GMs Romanishin and Tisdall, and IM Remlinger of course.