Same recommendation on the book if you're using VC papers. It's where I got my numbers, and explains how to test for yourself using the Stouffer step wedges.
Ctein also gives well-deserved attention to tonal distribution throughout the range of the papers, not just the total range. He'll need to re-do those illustrations for the next edition, since 3 of the 4 tested papers are no longer available. But the illustrations make clear the need for testing/awareness of the differences in the curve shapes of the papers, and of different VC filters.