Shiva Purana
अकार उत्तरात्पूर्वमुकारः पश्चिमाननात् । मकारो दक्षिणमुखाद्बिंदुः प्राण्मुखतस्तथा १८ ।
The syllable “A” came first from northern face; the syllable “U” from the western; the syllable “M” from the southern and the Bindu (dot) from the eastern face.
english translation
akAra uttarAtpUrvamukAraH pazcimAnanAt । makAro dakSiNamukhAdbiMduH prANmukhatastathA 18 ।
hk transliteration by Sanscript