Shiva Purana
तत्राद्यो मातृकान्यासो ब्रह्मन्यासस्ततः परः ॥ तृतीयः प्रणवन्यासो हंसन्यासस्तदुत्तरः ॥ २२ ॥
The first of these is the matrix, and the next is the Brahman. The third is the oṁkāra-nyasa, and the next is the swan-nyasa.
english translation
tatrAdyo mAtRkAnyAso brahmanyAsastataH paraH ॥ tRtIyaH praNavanyAso haMsanyAsastaduttaraH ॥ 22 ॥
hk transliteration by Sanscript