  For $\Gamma_1$-structures on 3-manifolds, we give a very simple proof of
Thurston's regularization theorem, first proved in \cite{thurston}, without
using Mather's homology equivalence. Moreover, in the co-orientable case, the
resulting foliation can be chosen of a precise kind, namely an "open book
foliation modified by suspension." There is also a model in the non
co-orientable case.
