Calm down people.
The thing about an SQLi tutorial looking almost the same as the other is that most of them use the same definitions and overall structure. Now if they aren't using synonyms all the time and changing the voice, they would look real similar.
Now you can be sure that nobody would like to write this long a tutorial from scratch (I did in old VF, made a very basic Calculator tutorial and I regret it. It just took too long).
So yes there can be partial similarity in most of the tutorials. Like this one looks almost like
The Ultimate Structured Query Language Injection Tutorial., even the spelling mistake of 'sites' in "Finding SQLI Vulnerable sits".
You can add a credits list, where did you get definitions, overall frame, dorks etc. in the thread from now on if you like and if you can remember.
But it would be ridiculous to point out every line of information you've used, and posting 20-30 lines of Credits, so the major source would be more appropriate.