@article{DMGT_2022_42_3_a18,
     author = {Lyu, Zhenhua},
     title = {Extremal {Digraphs} {Avoiding} {Distinct} {Walks} of {Length} 4 with the {Same} {Endpoints}},
     journal = {Discussiones Mathematicae. Graph Theory},
     pages = {985--1004},
     publisher = {mathdoc},
     volume = {42},
     number = {3},
     year = {2022},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/DMGT_2022_42_3_a18/}
}