A co-occurrence map I used a so-called “map of science” to illustrate various parts of this page. It is based on real metadata about biomedical publications! As every other scientific discipline, biomedical researchers use different publication types to write down and communicate their findings. For example, you can publish your results as a book, a journal article or in a newspaper. These “publication types” are assigned to each study by the PubMed database which includes over 30 million publications.