On Postnikov-true families of complexes and the Adams completion Aristide Delenau, Peter Hilton (1980) Fundamenta Mathematicae
On the center of the fundamental group of the complement of a hyperplane arrangement. Cordovil, Raul (1994) Portugaliae Mathematica
On the homotopy groups of a finite dimensional space. C.A. McGibbon, J.A. Neisendorfer (1984) Commentarii mathematici Helvetici