On the difference between consecutive squarefree integers S. Graham; G. Kolesnik — 1988 Acta Arithmetica
An estimate for the number of reducible Bessel polynomials of bounded degree M. Filaseta; S. Graham — 1993 Colloquium Mathematicae
Holonomy and projective equivalence in 4-dimensional Lorentz manifolds. Hall, Graham S.; Lonie, David P. — 2009 SIGMA. Symmetry, Integrability and Geometry: Methods and Applications [electronic only]