E. Further reading and real codebases worth reading

• The C Programming Language (K&R, 2nd ed.) — dated in places (pre-C99) but still the sharpest, shortest tour of the language's core ideas.
• Modern C (Jens Gustedt, free online) — written around C11/C17, the best bridge from "K&R C" to the standard this guide targets.
• SQLite source (sqlite.org) — Section 33; read os_unix.c for the VFS layer, vdbe.c for the opcode interpreter.
• Redis source (github.com/redis/redis) — Section 34; start with src/sds.c and src/ae.c, both short and self-contained.
• curl source (github.com/curl/curl) — Section 35; lib/easy.c and lib/multi.c.
• cJSON source (github.com/DaveGamble/cJSON) — Section 36; small enough to read start to finish in one sitting after this guide's Part II.
• The Linux kernel's include/linux/list.h — Section 19's container_of, in its original, real-world form.
• man 7 signal, man 2 mmap, man 3 pthread_create — the primary sources this guide's socket/threading/memory sections summarize; the man pages are the actual specification of the syscalls you're calling.
• wiki/DSA/real-life-ds-algo-guide.md — this guide's data-structures-and-algorithms companion. It covers every classic DS/algo topic (arrays through Dijkstra and topological sort) ELI5-first, with a Go implementation and a C implementation side by side for each one — the C versions are the beginner on-ramp to Sections 17–23's from-scratch data structures and Section 22's Dijkstra/graph material above, in the same toy-box-analogy style as this guide's "Real-world example" boxes.