Conceptualization of the research questions.

<p>Starting from the article <i>i</i> written by α,β and γ and published in year t, two networks are derived. On the left side, the co-authorship network shows that α is already part of a group of other authors and had joint works with two of them (represented by the two edges inside the author set). β and γ are connected to the set of authors through α by means of their new joint-work <i>i</i>. We then extract three measures, degree, closeness and betweenness for each co-author of <i>i</i>, and map only the maximum value into <i>i</i>. On the right side, the article <i>i</i> have common references with articles of the sets A and B. We measure the degree, betweenness centralities and clustering coefficient of the article <i>i</i>. We construct the dependent variable cumulating the citations received by article <i>i</i> in the two years following the year of its publication. Last, we verify the effects the co-authorship and bibliographic coupling networks measures on the citation count of article <i>i</i>.