Okay, found it: Native Genius in Anonymous Architecture by Sibyl Maholy-Nagy, published in 1957 by Horizon Press of New York. I have a copy on the way by inter-library loan. Thanks for the heads-up on that book

Page 130 of the book, you will find the picture and the very slight tilt of the wall. It would be interesting to hear your opinion on the book as a whole.

I go back and forth as to which is more efficient, a hipped roof or a gable end wall? One requires more framing but is simpler in other ways. With natural infills I lean toward the hip, no need to take the infill into the gable end and it gives the chance to form a reasonable overhang.

Tim