We are interested in multimodal systems that use the following modes and modalities : speech (and natural language) as input as well as output, gesture as input and visual as output using screen displays. The user exchanges with the system by gesture and/or oral statements in natural language. This exchange, encoded in the different modalities, carries the goal of the user and also the designation of objects (referents) needed to achieve this goal. The system must identify in a precise and non-ambiguous way the objects designated by the user. In this document, we expose a state of the art about the processing of referential activities in this particular context.We address methods and algorithms of processing of linguistic and multimodal referential activities. We also address problems relied to some designations by gesture. Our point of view is to situate studies and results within the framework aiming to propose generic solutions and to develop the GEORAL multimodal system.