This paper presents the results of a terminological work conducted by the authors on a Digital Archives Net of the Italian National Research Council (CNR) in the field of Computer Science. In particular, the research tends to analyse the use of certain terms in Computer Science in order to verify their change over the time with the aim of retrieving from the net the very essence of documentation. Its main source is a reference corpus made up of 13,500 documents which collects the scientific productions of CNR. This study is divided in three sections: 1) an introductory one dedicated to the data extracted from the scientific documentation; 2) the second section is devoted to the description of the contents managed by the PUMA system; 3) the third part contains a statistical representation of terms extracted from archive: some comparison tables between the occurrences of the most used terms in the scientific documentation will be created and diagrams with percentages about the most frequently used terms will be displayed too. Indexes and concordances will allow to reflect on the use of certain terms in this field and give possible keys for having access to the extraction of knowledge.