Is thereDoes someone who knowsknow some booksbook or lecture notes useful for the reading of the paper
"A construction of the fundamental solution for the Schrödinger equation", Fujiwara, Daisuke, J. Analyse Math.J. Analyse Math. 35 (1979), 41–96. ?
In particular I'm looking for references for a better understanding of the concepts of Feynman's path integral and the construction of the parametrices.