Ali Enayat. δ as a Continuous Function of x and ε. The American Mathematical Monthly, 107(2):151-155, 2000. [doi]
@article{Enayat00, title = {δ as a Continuous Function of x and ε}, author = {Ali Enayat}, year = {2000}, url = {http://www.jstor.org/stable/2589436}, researchr = {https://researchr.org/publication/Enayat00}, cites = {0}, citedby = {0}, journal = {The American Mathematical Monthly}, volume = {107}, number = {2}, pages = {151-155}, }