There appears to be a lot of confusion on this with photographers, because many use lpm for lines per millimeter. But lines per millimeter in Williams' text is understood to mean line pairs per millimeter.The book was published in 1990, in the very early days of digital imagery. But it is still a good read.
Frankly there would be no need for me to get out a chart and try to resolve (pun) the issue with my eyes. I used to have 20/20 vision but now have very severe astigmatism in one eye, and the other is myopic and has a cataract that will need to be removed in a year or so. Also, I had a retinal tear last year in the myopic eye that caused some loss of vision. Fact of the matter I should probably quite talking about high resolution imagery and start working wth one of these "artsy fartsy" Holga cameras, or even the mythical Diana if I could afford one of those plastic marvels.