Norway in UFO Photographs: The First Catalogue (with O.J. Braenne), UPIAR, 2008, https://upiar.com/italian-norway2
The Marfa Lights. Examining the Photographic Evidence (2003-2007) (with M. Borraz), UPIAR, 2020, https://upiar.com/italian-marfa2
The Reliability of UFO Witness Testimony (eds.) (with R.W. Heiden), UPIAR, 2023, https://upiar.com/item.cfm?articoloid_rw=reliability2
Mi correspondencia con Antonio Ribera (My Correspondence with Antonio Ribera), UPIAR, 2024, https://upiar.com/item.cfm?articoloid_rw=ribera2
Mi correspondencia con José-Tomás Ramírez y Barberó (My Correspondence with José-Tomás Ramírez y Barberó), UPIAR, 2025, https://upiar.com/item.cfm?articoloid_rw=ramirez2