Gaura-gopala mantra-mantra composed of the four syllables ra-dha-krs-na.
Gaura Mantra the four syllable mantra is ”gau-ra-an-ga”
Srila Bhaktivinoda Thakura explains the Gaura-gopala mantra in his Amrta-pravaha-bhasya. Worshipers of Sri Gaurasundara accept the four syllables gau-ra-an-ga as the Gaura mantra, but pure worshipers of Radha and Krsna accept the four syllables ra-dha krs-na as the Gaura-gopala mantra. However, Vaisnavas consider Sri Caitanya Mahaprabhu nondifferent from Radha-Krsna