1. All graphs in which each pair of distinct vertices has exactly two common neighbors Creator: Stevanović, Dragan Format: bez média and svazek Type: model:article and TEXT Subject: graphs, adjacency matrix, eigenvalues of a graph, and common neighbours Language: English Description: We find all connected graphs in which any two distinct vertices have exactly two common neighbors, thus solving a problem by B. Zelinka. Rights: http://creativecommons.org/publicdomain/mark/1.0/ and policy:public