At the end of 1954, Eduardo Ducay, Juan Julio Baena and Carlos Saura travelled to the region of Sanabria (province of Zamora) to make a commissioned documentary on the construction of a system of reservoirs. Much of the filmed material was unusable due to a technical problem, but Ducay rescued part of it and combined it with voice-over to construct a work on absences.
Unfortunately the movie Letter of Sanabria is not yet available on Disney Plus.
| Directing | Eduardo Ducay | Director |
| Writing | Eduardo Ducay | Writer |
| Crew | Juan Julio Baena | Cinematography |
| Camera | Carlos Saura | Assistant Camera |
| Editing | Carlos Llanos | Editor |
| Editing | Alfonso Santacana | Editor |
| Sound | Juan Flierbaum | Sound |