Hathayoga 1-22

Gomukhaâsana

सव्ये दक्षिण-गुल्कं तु पृष्ठ-पार्श्वे नियोजयेत् ।

दक्षिणेऽपि तथा सव्यं गोमुखं गोमुखाकृतिः ॥ २२॥

Savye dakshinaghulpham tu prshthapārśve niyojayet Dakshineapi tathā savyam ghomukham ghomukhākrtih

Placing the right ankle on the left side and the left ankle on the right side, makes Gomukhaâsana, having the appearance of a cow.