Publishing and The Three Angels' Messages

In the Advantages and Benefits page, we see

Then I saw another angel flying in the midst of heaven, having the everlasting gospel to preach to those who dwell on the earth–to every nation, tribe, tongue, and people (Revelation 14:6).
And in a large degree through our publishing houses is to be accomplished the work of that other angel who comes down from heaven with great power and who lightens the earth with his glory. PM 50.2

How can literature help to fulfill this?