Robert E. Woodrow. There are four countable ultrahomogeneous graphs without triangles. Journal of Combinatorial Theory, Series A, 27(2):168-179, 1979. [doi]
@article{Woodrow79,
title = {There are four countable ultrahomogeneous graphs without triangles},
author = {Robert E. Woodrow},
year = {1979},
doi = {10.1016/0095-8956(79)90078-9},
url = {http://dx.doi.org/10.1016/0095-8956(79)90078-9},
tags = {graph-rewriting, e-science, rewriting},
researchr = {https://researchr.org/publication/Woodrow79},
cites = {0},
citedby = {0},
journal = {Journal of Combinatorial Theory, Series A},
volume = {27},
number = {2},
pages = {168-179},
}