This is not exactly NeXTSTEP related, but still of historic importance:
https://archive.org/details/utah_unix_v4_raw (https://archive.org/details/utah_unix_v4_raw)
Related mastodon discussion providing context and further details:
https://discuss.systems/@ricci/115504720054699983 (https://discuss.systems/@ricci/115504720054699983)