Shiva Purana
रेचकः पूरकः कुम्भः प्राणायामस्त्रिधा स्मृतः ॥ नाडीसंचारविज्ञानं प्रत्याहारनिरोधनम् ॥ २०॥
There are three types of pranayama: laxative, supplementary and aquatic. The science of pulse circulation is the inhibition of retraction.
english translation
recakaH pUrakaH kumbhaH prANAyAmastridhA smRtaH ॥ nADIsaMcAravijJAnaM pratyAhAranirodhanam ॥ 20॥
hk transliteration by Sanscript