  We study the network structure of Wikipedia (restricted to its mathematical
portion), MathWorld, and DLMF. We approach these three online mathematical
libraries from the perspective of several global and local network-theoretic
features, providing for each one the appropriate value or distribution, along
with comparisons that, if possible, also include the whole of the Wikipedia or
the Web. We identify some distinguishing characteristics of all three
libraries, most of them supposedly traceable to the libraries' shared nature of
relating to a very specialized domain. Among these characteristics are the
presence of a very large strongly connected component in each of the
corresponding directed graphs, the complete absence of any clear power laws
describing the distribution of local features, and the rise to prominence of
some local features (e.g., stress centrality) that can be used to effectively
search for keywords in the libraries.
