Shiva Purana
ततः पश्चिमदिक्पत्रे सह शक्त्या शिवोत्तमम् ॥ तथैवोत्तरदिक्पत्रे चैकनेत्रं समर्चयेत् ॥ ७ ॥
Then in the western petal he shall worship lord Śiva along with his Śakti. Similarly in the northern petal he shall worship Ekanetra and his Śakti.
english translation
tataH pazcimadikpatre saha zaktyA zivottamam ॥ tathaivottaradikpatre caikanetraM samarcayet ॥ 7 ॥
hk transliteration by Sanscript