To cite the BeFree system in your publications:
À. Bravo, M. Cases, N. Queralt-Rosinach, F. Sanz, and L. I. Furlong, “A Knowledge-Driven Approach to Extract Disease-Related Biomarkers from the Literature,” BioMed Research International, vol. 2014, Article ID 253128, 11 pages, 2014. doi:10.1155/2014/253128. (Article, for the "Big Data and Network Biology" special issue at BioMed Research International).
To cite specific data:
Gene–disease association data were extracted from MEDLINE®/PubMed®, a database of NLM or the U.S. National Library of Medicine, by application of the BeFree system, GRIB/IMIM/UPF Integrative Biomedical Informatics Group, Barcelona. (http://ibi.imim.es/befree/). [Month, year of data retrieval].