Douglas S. Bridges. How to construct a product of a-frames. Math. Log. Q., 58(4-5):281-293, 2012. [doi]
@article{Bridges12-0, title = {How to construct a product of a-frames}, author = {Douglas S. Bridges}, year = {2012}, doi = {10.1002/malq.201110059}, url = {http://dx.doi.org/10.1002/malq.201110059}, researchr = {https://researchr.org/publication/Bridges12-0}, cites = {0}, citedby = {0}, journal = {Math. Log. Q.}, volume = {58}, number = {4-5}, pages = {281-293}, }