On the Cohomology of Spaces with Two Non-Vanishing Homotopy Groups. Leif Kristensen — 1963 Mathematica Scandinavica
On a Cartan Formula for Secondary Cohomology Operations. Leif Kristensen — 1965 Mathematica Scandinavica
A Secondary Product Structure in Cohomology Theory. Anders Kock; Leif Kristensen — 1965 Mathematica Scandinavica
On Evaluation of Higher Order Cohomology Operations. Ib Madsen; Leif Kristensen — 1967 Mathematica Scandinavica
The ...-Module Structure for the Cohomology of Two-Stage Spaces. Erik K. Pedersen; Leif Kristensen — 1972 Mathematica Scandinavica