The minimum values of positive quadratic forms in sex, seven and eight variables H.F. Blichfeldt — 1935 Mathematische Zeitschrift
The Finite, Discontinous, Primitive Groups of Collineations in Three Variables H.F. Blichfeldt — 1907 Mathematische Annalen
The Finite, Discontinuons Primitive Groups of Collineations in Four Variables H.F. Blichfeldt — 1905 Mathematische Annalen
The Minimum Value of Quadratic Forms, and the Closest Packing of Spheres H.F. Blichfeldt — 1929 Mathematische Annalen