Shiva Purana
पञ्चकं त्रिकमेकं वा प्राणायामं समाचरेत् ॥ अगर्भं वा सगर्भं वा सगर्भस्तत्र शस्यते ॥ ३२ ॥
He shall perform five, three or one Prāṇāyāma whether Agarbha or Sagarbha. The Sagarbha Prāṇāyāma is better of the two.
english translation
paJcakaM trikamekaM vA prANAyAmaM samAcaret ॥ agarbhaM vA sagarbhaM vA sagarbhastatra zasyate ॥ 32 ॥
hk transliteration by Sanscript