Stephen K. Lucas. Approximations to π Derived from Integrals with Nonnegative Integrands. The American Mathematical Monthly, 116(2):166-172, 2009. [doi]
@article{Lucas09-3,
title = {Approximations to π Derived from Integrals with Nonnegative Integrands},
author = {Stephen K. Lucas},
year = {2009},
url = {http://www.jstor.org/stable/27642693},
researchr = {https://researchr.org/publication/Lucas09-3},
cites = {0},
citedby = {0},
journal = {The American Mathematical Monthly},
volume = {116},
number = {2},
pages = {166-172},
}