It is now considered that the information available in bibliographical databases is dated, validated through a long process which does not make it very innovative. Furthermore, database processing is normally performed using boolean operators : the results obtained from a query provides a sum of expected information which, in itself, does not deliver any novelty. Don Swanson's work demonstrates the unsuspected potential of bibliographical databases in revealing and discovering knowledge.The interest of his approach lies less on the available information itself than on the methodology used to disclose new knowledge. This general methodology fits perfectly well within an environment of validated and structured information, as is the case for bibliographical data. The expression Knowledge Discovery in Databases (KDD) indicates a methodology which creates new knowledge based upon bibliographical data. In this article, we will cover the principals of KDD based on Don Swanson's work as well as the method used to disclose knowledge within biomedical bibliographical databases.