You are right in the aspect that I should have mentioned the sources.
I did it because I don't believe you deserve being rewarded for the ideas and content someone else wrote.
Would you still downvote if I would use something licensed under creative commons (CC), GNU, MIT, BSD (or any similar) license, which allows all kinds of (even commercial) usage? I would mention the author and the source, of course.
I would not but if your post consisted of only that I wouldn't upvote it either.
I learned the lesson. If I will use someone else's content, then I will mention the sources.
Have a nice weekend mate. Enjoy a beer if you're into that.