Douglas S. Bridges. Product a-frames and proximity. Math. Log. Q., 54(1):12-26, 2008. [doi]
@article{Bridges08, title = {Product a-frames and proximity}, author = {Douglas S. Bridges}, year = {2008}, doi = {10.1002/malq.200710033}, url = {http://dx.doi.org/10.1002/malq.200710033}, researchr = {https://researchr.org/publication/Bridges08}, cites = {0}, citedby = {0}, journal = {Math. Log. Q.}, volume = {54}, number = {1}, pages = {12-26}, }