As in the people I reblogged them from or the original website? I used to credit users but Tumblr has made it where it doesn’t always list the users. It’s too much of a hassle now and you can just view the same information under notes or the source/via thing on my actual page. For websites, usually unless they prefer it, I don’t credit because most of the time, they’re not the original source or creator/author/etc. It takes one extra step out of posting for me, and if you’re that curious, then look up the information that I post. I gladly do it all the time and I end up finding a lot more than I wanted.
ETA: You’re also welcome to ask me where I got them from if you can’t find anything. I have no problem with it and I’ve actually helped quite a few people about it before.