Hathatattvakaumudi

Haṭhatattvakaumudī (हठतत्त्वकौमुदी) represents an 18th-century text on Haṭhayoga consisting of fifty-six chapters and approximately 1680 verses.—The Haṭhatattvakaumudī has five chapters on prāṇāyāma (9, 10, 12, 37–38), namely, the preliminary auxiliaries and rules of practice for prāṇāyāma, an explanation of the names, nature and characteristics of kumbhakas, breathing methods for quelling suffering, necessary rules for prāṇāyāma and an explanation of prāṇāyāma, which total more than 240 verses.

Source: ORA: Amanaska (king of all yogas): A Critical Edition and Annotated Translation by Jason Birch

Haṭhatattvakaumudī (हठतत्त्वकौमुदी) is a large compendium on yoga of approximately two thousand and forty-eight verses, the majority of which are written in a higher register of Sanskrit than most yoga texts. The final colophon reveals that the author was a Brahmin by the name of Sundaradeva. [...] Like Śivānanda's Yogacintāmaṇi, the Haṭhatattvakaumudī appears to have been written for the more learned Brahmin, and it quotes from a similar range of sources, namely a variety of Yoga texts, Upaniṣads, Epics, Purāṇas, Dharmaśāstras and so on. Sundaradeva knew the work of Śivānanda and Kavīndrācārya.