Perhaps you should try some spelling variations:
"path integral formulation" » "path lineal formulacion", "parte integral formulation", "la integral formulation"
"et integral formulation" » "et lineal formulacion", "e integral formulation", "_ integral formulation", "la integral formulation"
"de integral formulation" » "de lineal formulacion", "e integral formulation", "de integrar formulation", "de integrales formulation"

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