| Tretter, Robert E.; 1975 ASC Appointment List; 1975 | 1975 ASC Appointment List | 1975-00-00 | MCKEE SONS | First Mate |
| Tretter, Robert E.; 1979 Red Book; 1979 | 1979 Red Book | 1979-00-00 | JOHN T. HUTCHINSON | Captain |
| Tretter, Robert E.; 1981 Red Book; 1981 | 1981 Red Book | 1981-00-00 | JOHN T. HUTCHINSON | Captain |
| Tretter, Robert E.; 1983 Red Book; 1983 | 1983 Red Book | 1983-00-00 | NICOLET | Captain |
| Tretter, Robert E.; ASC Soundings 11(1)1991 | ASC Soundings 11(1)1991 | 1991-00-00 | NICOLET | Captain |
| Tretter, Robert E.; ASC Soundings 11(1)1991 | ASC Soundings 11(1)1991 | 1991-00-00 | | Captain |
| Tretter, Robert E.; ASC Soundings August1986 | ASC Soundings August1986 | 1986-00-00 | | Captain |
| Tretter, Robert E.; ASC Soundings May 1982 | ASC Soundings May 1982 | 1982-00-00 | NICOLET | Captain |
| Tretter, Robert E.; ASC Soundings May 1987 | ASC Soundings May 1987 | 1987-00-00 | SINALOA | Third Mate |
| Tretter, Robert E.; ASC Soundings May 1987 | ASC Soundings May 1987 | 1987-00-00 | AMERICAN REPUBLIC | Captain |
| Tretter, Robert E.; Soundings Feb 1988 | Soundings Feb 1988 | 1988-00-00 | | First Mate |
| Tretter, Robert E.; Soundings Feb 1988 | Soundings Feb 1988 | 1988-00-00 | JOHN T. HUTCHINSON | Captain |