An important resource for finding biological databases is a special yearly issue of the journal Nucleic Acids Research (NAR). The Database Issue of NAR is freely available, and categorizes many of the publicly available online databases related to biology and bioinformatics. A companion database to the issue called the Online Molecular Biology Database Collection lists 1,380 online databases.[4] Other collections of databases exist such as MetaBase and the Bioinformatics Links Collection.[5][6]