@article{10_1017_S0017089500000690,
     author = {Riddell, J.},
     title = {Sets of integers containing no n terms in geometric progression},
     journal = {Glasgow mathematical journal},
     pages = {137--146},
     year = {1969},
     volume = {10},
     number = {2},
     doi = {10.1017/S0017089500000690},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500000690/}
}