Ask HN: Can I use a survey developed by a university professor?

Hello HN,

I would like to use a survey developed by a university professor on our website legitimately. Unfortunately, this professor passed away in 1988. Since then there has been a number of academic publications that have used his surveys by simply citing his work.

Am I allowed to use his surveys providing I cite his work? Or are there a few more legal or copyright implications I need to consider and it is best to contact his former university and publisher?

I look forward to any guidance. Thank you.