Shiva Purana
नूतनं वै करोतीति प्रणवं तं विदुर्बुधाः । प्रणवं द्विविधं प्रोक्तं सूक्ष्मस्थूलविभेदतः ८ ।
The wise know that the Pranava (Om) is the new form, for it creates. The Pranava is said to be of two kinds: subtle and gross, distinguished by their forms.
english translation
nUtanaM vai karotIti praNavaM taM vidurbudhAH । praNavaM dvividhaM proktaM sUkSmasthUlavibhedataH 8 ।
hk transliteration by Sanscript