A growth model for citations networks

In some complex networks, nodes can continuously increase or decrease the number of their incoming and outgoing links. The World Wide Web is one such example, as webmasters can add or delete hyperlinks on web pages at any time. There are also networks where this can not happen. For instance, in citation networks of scientific articles, after an article has been published, it will start gaining incoming links as it is cited, but its outgoing links will remain unchanged. Although articles are published with a predetermined number of references, the distribution of their outgoing links follows a power law, as if they were the result of a preferential process. So, how can we explain that the number of references an author includes in a scientific article is not purely random? In this work, a growth model for citation networks is presented, proposing that the distribution of outgoing links can be shaped by the presence of communities.