How to correctly cite adapted and translated course lecture notes? I am making some lecture notes for a Computer Science course in my mother language, which is Italian. Some of my notes are based mostly on lecture notes by other professors. I do not copy and paste, but I paraphrase and put my own opinions in portions of the lecture notes. Apart from the references, I usually put this quote at the beginning of my lecture notes when it is necessary:


  "The following material is heavily based on the lecture notes by Professor X given at the University of Y during the course Z"


Is that enough? I would not like to be blamed for plagiarism or any academic misbehaviour for making a silly mistake.
For course lecture material, unlike scientific publications, there is no requirement for uniqueness.  It seems that you are giving clear attribution and credit (which can be nicely enhanced by a link, as @JeffE suggests), so I think the only further thing to do would be to drop a courtesy note to the original professor(s) to let them know how you are appreciatively using their material.  Likely they will be happy and knowing that you are using it may even be beneficial to them; in the unlikely event that they are displeased, then you should not use their material (and should ask them to post a clear statement to warn others not to do so either).