  This paper is a commentary and a reading guide to three papers by Herbert
Busemann, \"Uber die Geometrien, in denen die "Kreise mit unendlichem Radius"
die k\"urzesten Linien sind." (On the geometries where circles of infinite
radius are the shortest lines) (1932), "Paschsches Axiom und
Zweidimensionalit\"at," (Pasch's Axiom and Two--Dimensionality) (1933) and
"\"Uber R\"aume mit konvexen Kugeln und Parallelenaxiom (On spaces with convex
spheres and the parallel postulate) (1933). These are the first papers that
Busemann wrote on the foundations of geometry and the axiomatic
characterization of Minkowski spaces (finite-dimensional normed spaces). The
subject of these papers followed Busemann for the rest of his life, and the
three papers already contain several ideas and techniques that he developed
later on, in his work on the subject which lasted several decades. The three
papers were translated into English by Annette A'Campo. These translations,
together with the final version of present commentary, will be part of the
forthcoming edition of Busemann's Collected Papers edition.
