1. Chanting & Veda study

    rg-vedo ‘tha yajur-vedah
    sama-vedo ‘py atharvanah
    adhitas tena yenoktam
    harir ity aksara-dvayam

    “A person who chants the two syllables ha-ri has already studied the four Vedas-Sama, Rg, Yajur and Atharva.”

    Quoted in Srila Prabhupada’s purport to Sri Caitanya-caritamrta Adi-lila 7.72