Shiva Purana
श्रीमन्त्रिशूलमैशाने वज्रं माहेन्द्रदिङ्मुखे ॥ परशुं वह्निदिग्भागे याम्ये सायकमर्चयेत् ॥ ६६ ॥
The trident of the goddess of fortune is in the north-east, and the thunderbolt is in the south-facing Gaindra. One should worship the ax and the arrow on the southern side of the fire.
english translation
zrImantrizUlamaizAne vajraM mAhendradiGmukhe ॥ parazuM vahnidigbhAge yAmye sAyakamarcayet ॥ 66 ॥
hk transliteration by Sanscript