Shiva Purana
इत्थं प्रणवविन्यासं कृत्वा न्यासविचक्षणः॥ हंसन्यासं प्रकुर्वीत परमात्मविबोधिनि ॥ ७७ ॥
Thus having arranged the oṁkāra, the expert in the installation. One should perform the swan-nyasa in the realization of the Supreme Self.
english translation
itthaM praNavavinyAsaM kRtvA nyAsavicakSaNaH॥ haMsanyAsaM prakurvIta paramAtmavibodhini ॥ 77 ॥
hk transliteration by Sanscript