Tantra Sāra 1.012
अनिरुद्धादिकास्तासां देवता व्युत्क्रमेण वा। ताश्चतुर्मूर्तयस्त्वेव द्वादशार्णपदोदिताः ॥१२॥
aniruddhādikāstāsāṁ dēvatā vyutkramēṇa vā। tāścaturmūrtayastvēva dvādaśārṇapadōditāḥ ॥12॥
[aniruddhādikāstāsāṁ = lord Aniruddha; dēvatā = and other forms i.e., Pradyumna, Sankarshana, and Vāsudeva; vyutkramēṇa vā = manifest in order; tāścaturmūrtayastvēva = These four forms of the lord only; dvādaśārṇapadōditāḥ = are indicated by the tweleve letters of the twelve letter mantra;]
Lord Aniruddha and other forms (i.e., Pradyumna, Sankarshana, and Vāsudeva) manifest in order (from the four Vyahritis). These four forms of the lord only are indicated by the letters of the twelve letter mantra.
Note:
In the tweleve letter mantra, "Ōm Na-Mō Bha-Ga-Va-Tē Vā-Su-Dē-Vā-Ya", Ōm = Aniruddha, Namō = Pradyumna, Bhagavate = Sankarshana, and Vāsudevaya = Vāsudeva, forms of the lord.
A pictorial representation:
