I am looking for a specific paper by Gray/Vanhecke with the title
"The volumes of tubes in a Riemannian manifold"
published in 1981. Note that there is another paper with the title "The volumes of tubes about curves in a Riemannian manifold" which was published in 1982, and that this is not the paper I am looking for for. So far I did not find any way of accessing this paper, be it free or behind a paywall. Any source for access to this paper would be very appreciated.
In this list of publications, it says it was published in Rendiconti del Seminario Matematico Universitá e Politecnico Torino.
https://web.archive.org/web/20050213080244/http://www.ehu.es/gray/publications.html
In the site of the Seminario, you can ask them for the reference, or at least it's what they say.
http://www.seminariomatematico.unito.it/rendiconti/cartaceo/39-3.html
Also, there's this book in his honour«Global Differential Geometry: The Mathematical Legacy ·of Alfred Gray ». It might be useful.
And good luck in your search and study.