Mai Gehrke. D-Separation Axiom. Math. Log. Q., 37(1):5-15, 1991. [doi]
@article{Gehrke91-0, title = {D-Separation Axiom}, author = {Mai Gehrke}, year = {1991}, doi = {10.1002/malq.19910370103}, url = {http://dx.doi.org/10.1002/malq.19910370103}, researchr = {https://researchr.org/publication/Gehrke91-0}, cites = {0}, citedby = {0}, journal = {Math. Log. Q.}, volume = {37}, number = {1}, pages = {5-15}, }