ललितोपाख्याने जप-न्यास-योगप्रकरणम्
Lalitopākhyāna: Procedure of Japa, Nyāsa, and Yogic Installation
शषसा इति विख्याता द्विचत्वारिंशदक्षराः / आद्यः पञ्चाक्षरो वर्गो द्वितीयश्चतुरक्षरः
śaṣasā iti vikhyātā dvicatvāriṃśadakṣarāḥ / ādyaḥ pañcākṣaro vargo dvitīyaścaturakṣaraḥ
These are famed as “śaṣasā”, consisting of forty-two letters. The first group is of five letters; the second is of four.