Permission for using publicly available questionnaires in Dissertations I have used and/or adapted several questionnaires for my dissertation study. I have already asked the authors for permission to use their scales. However, I have not received a reply from an author about using his scale.

I wonder if we have to have the permission of the authors when we use their surveys (when the questionnaire items are published and publicly available), or is it a courtesy to ask for the permission. Is it still okay to use a public scale when no confirmation is received from the author who developed the scale?

Thanks for any suggestions!
Cite them.

If the questionnaires are published then you do not need to ask for permission, just give them credit. 

In Psychology there are some very popular questionnaires that were presented in papers that have been cited more than 5000 times. It would be a full-time job to reply to every person's email who wants to use it!