- Letter written in 1998 by Mario Bruschi, Professor at the Physic Department of University "La Sapienza" in Rome.
"I believe that in this kind of experiments ["anomalous perception"] the many
and high developed PSI abilities of Umberto Di Grazia could be fruitfully exploited..."
- Letter written in 1999 by Francesco Bruno, criminologist, Chair of Forensic Psycopathology at the Psychiatric Sciences and Psychological Medicine Department
of University "La Sapienza" in Rome.
(italian version) (english version)
- "FEDE, MISTERO, MAGIA. LETTERE A UN SENSITIVO"
by M. Immacolata Macioti (Chair of Sociology at the University “La Sapienza” of Rome), Dedalo Editions, Bari, 1991
“Faith, Mistery, Magic: letters to a psychic”, her publication on Umberto di Grazia, has become an exam test at the Faculty of Sociology of La Sapienza University, Rome.