I noticed the same thing, especially with many of those old authoritative sources that seem to have disappeared or suffered from link rot. It reminds me a lot of the movie Soylent Green, where basic repairs had to be done custom because there were no replacements. Outside of academic journals and printed books, I don’t bother searching for information because it’s just not worth the effort given how hard it is to find reliable sources. The only way I’ve been dealing with this is by relearning my fundamentals. There are only so many ways hardware and software can be designed correctly, so I rely on recurring patterns, motifs, improving my reverse engineering skills, and adopting a clean-room design approach.