maximal function, Maximal functions, Littlewood-Paley theory, martingale, atom, \(H^p\)-spaces, Spaces of measurable functions (\(L^p\)-spaces, Orlicz spaces, Köthe function spaces, Lorentz spaces, rearrangement invariant spaces, ideal spaces, etc.), quadratic variation, Martingales and classical analysis, duality, Martingales with discrete parameter, Function spaces arising in harmonic analysis, Musielak-Orlicz Hardy space, conditional quadratic variation