@masterthesis{3218304,
    title = "Multiple-Scale perturbative method and its application in cosmological perturbations",
    authorField = "Σάρρας, Ορέστης",
    year = "2022",
    school = "ΠΜΣ Φυσική, Εθνικό και Καποδιστριακό Πανεπιστήμιο Αθηνών"
}