Research process generates public and formal informations accessible through published documents or public data bases which libraries are used to deal with. It also generates informal, anachieved informations in format of correspondances, notes, calculus, reports, drawings... or other unpublished documents that libraries must not either leave aside.

Since fundamental research, versus technological research for instance, implies great personal involvement, informal informations are mainly issued from individuals or small groups of individuals. It is probably the reason why this kind of informations and documents is often considered erronously as private by astronomers deciding by themselves to destroy, to move or leave behind their so-called personal papers. These documents and informations actually belong to the institutions. They must be preserved because they are part of the research production and also because they may be used for astronomical research as it is illustrated in S. Débarbat’s communication.