@DivingInSpace There's three different titles you can borrow from your local library through the interlibrary loan system in US.
1. Lyle Murphy's system of Horizontal composition based on equal intervals. (This, from what I gather from other threads in this forum, is book 1 & 2 of the course, as it is taught today).
2. New music of a 12-tone system
3. Complete course in modern harmony, composition and orchestration for dance band, radio and motion pictures: A set of 4 books (incidentally also available online through the NYPL's digital collections archive:
https://digitalcollections.nypl.org...c#/?uuid=4df4a880-af6f-0134-e120-00505686a51c)
These titles read more like a workbook than a text book. Lyle Murphy says in the introduction that the emphasis is on the musical material presented and not wordage and is meant to be worked out on the piano. I like self learning so I'm quite enjoying working through the exercises in these books on my own. But I've caught myself going too fast a couple of times already only to later realize I misunderstood the material, as
@Craig Sharmat says.