Slightly more recent: The Design and Implementation of the 4.4 BSD Operating System, which includes some of the Berkeley additions to the kernel, such as TCP/IP

Slightly more recent: The Design and Implementation of the 4.4 BSD Operating System, which includes some of the Berkeley additions to the kernel, such as TCP/IP and sockets. And then there's xv6 [1], a small Unix running on vx32 from MIT for teaching purposes, full of comments, and available as a booklet that is directly inspired by Lions' commentary on the 6th edition of Unix. I actually agree, though: to really appreciate the classics you should start with (Maurice) Bach. :-P [1] https://pdos.csail.mit.edu/6.828/2018/xv6.html https://pdos.csail.mit.edu/6.828/2018/xv6.html