Naissance des feuilletages
(A unique and fascinating survey of the development of the subject from
1942 to 1970, by André Haefliger.)
Foliations and Foliated Vector Bundles
(Lecture notes from a course given at MIT in Fall 1969 by John Milnor.
This is a 7.5MB PDF file, scanned from 62 mimeographed pages.)
Foliations
(An introdction to foliations by Raymond Barre and Aziz El Kacimi Alaoui)