  We give a detailed, self-contained proof of Geoffrey Martin's normal form
theorem for Lagrangian submanifolds of standard multisymplectic manifolds (that
generalises Alan Weinstein's famous normal form theorem in symplectic
geometry), providing also complete proofs for the necessary results in foliated
differential topology, i.e., a foliated tubular neighborhood theorem and a
foliated relative Poincar\'e lemma.
