Rho, Yoomi et al., Minimum orders of eulerian oriented digraphs with given diameter, Acta mathematica Sinica. English series (Print) , 30(7), 2014, pp. 1125-1132
A digraph D is oriented if it does not contain 2-cycles. If an oriented digraph D has a directed eulerian path, it is an oriented eulerian digraph. In this paper, when an oriented eulerian digraph D has minimum out-degree 2 and a diameter d, we find the minimum order of D. In addition, when D is 2-regular with diameter 4m (m . 2), we classify the extremal cases.