Volume 57, Number 1, May 1991
: Projective equivalence of matroids with coefficients.
Gerhard J. M. van Wee
: Bounds on packings and coverings by spheres in q-ary and mixed Hamming spaces.
: Counting complements in the partition lattice, and hypertrees.
: An infinite number of plane figures with Heesch number two.
Volume 57, Number 2, July 1991
James A. Davis
: A result on Dillon's conjecture in difference sets.
: A completion of Lu's determination of the spectrum for large sets of disjoint Steiner triple systems.
H. F. Mattson Jr.
: Simplifications to "A new approach to the covering radius...".