I read this paper Inversion Based Direct Position Control and Trajectory Following for Micro Aerial Vehicles and despite of google it, I did not found any implementation source. if someone has a link for how it's implemented, I'd be grateful.
I haven't search for that particular method but I'm going to answer this question as a question on how to find if a given algorithm as a public implementation.
There is three steps (that I use) to find a given public implementation, if it exist:
search for it on GitHub. Usually the implementation will be available on GitHub if it's available somewhere. Bonus point if the repo is the one of the lab's university.
The lab's website. This paper was written by a lab that probably has a website and a personal page for each person. You might find the software available here, and the conditions for using it.
Finally, if you haven't found it yet, it's time to directly write to the author to ask if he has an implementation that you could use. Be sure to state what you will be doing with it and why you need it.