@article{1966-erdos
,author={Paul Erd\H os and Jack H. van Lint}
,ISSN={0037--5454}
,journal={Simon Stevin}
,MR={35:2836}
,pages={73--76}
,title={{On the number of positive integers $\le x$ and free of prime factors $>y$}}
,volume={40}
,year={1966}
}