As far as I am aware, the main book in English that covers the original organization of the Samyutta Nikaya and Samyukta Agama, is the one by Choong Mun-Keat:
The Fundamental Teachings of Early Buddhism: A Comparative Study Based on the Sutranga Portion of the Pali Samyutta-Nikaya and the Chinese Samyuktagama
Description:
This book is a comparative examination of the main teachings contained in the Sutranga portion of the Pali Samyutta-nikaya (SN) and its counterpart in Chinese canon, a translation of a now lost Sanskrit Samyuktagama (Za-ahan-jing) (SA). The SN and SA are essentially two different versions of the same collection of discourses.This study builds on the work of Yin Shun, which demonstrates the historical importance of SN/SA in the formation of the early Buddhist canon. In particular, it is based on Yin Shun’s recognition of the three-anga structure of SN/SA, and of the status of its Sutranga portion as of prime importance in the historical formation of this nikaya/agama, and as containing the most fundamental teachings of Buddha. The aim of this research is to reveal and clarify the similarities and differences between SN and SA, with regard to the principal Buddhist teachings contained in their Sutranga portion.
It’s been quite awhile since I read through it, but basically one of the main ideas is that there were originally three angas in the SA / SN, which were sutra, geya, and vyakarana. The sutra anga is believed to be the oldest of the three, and originally referred to a subset of the SA / SN.
Edit: Looks like there is already an old thread that has the vaggas of the sutta anga for the SN, that I believe are the ones that generally follow the sequence of the Four Noble Truths: