^Markstein, Don (2009). "Dagar the Invincible". Don Markstein's Toonopedia. Archived from the original on May 27, 2024. Dagar started as a non-series character, the hero of a story that writer Don Glut...wrote for Gold Key's Mystery Comics Digest...Tales Of Sword & Sorcery Starring Dagar the Invincible #1, dated October 1972. The artist was Jesse Santos, who worked with Glut on both Tragg and Spektor.
^Markstein, Don (2007). "Tragg and the Sky Gods". Don Markstein's Toonopedia. Archived from the original on May 27, 2024. Writer Don Glut...and artist Jesse Santos...supplied the comic, in which aliens from interstellar space had a profound effect on a tribe of Stone Age people.
^Markstein, Don (2007). "Doctor Spektor". Don Markstein's Toonopedia. Archived from the original on May 27, 2024. The Occult Files of Doctor Spektor...began with an April 1973 cover date. There, Glut's illustrative collaborator was Jesse Santos...who remained with the character and is now remembered as "the" artist on Doctor Spektor.