My notes. Honestly, though, I don't know; I keep them in my notes app wherever I read them. My only mistake is that I keep only the text and image part and no links to sources, as before saving, I already go through them.

See

I've been savimg thousands of them there since two years, as all of them help me a lot, and I share a few of them here. This one post I made is probably a mashup and taken from more sources, as it's in my mashup category. But I'll try to find the exact sources for you when I get time.