Agastya Samhita
Agastya Samhita (; ) is the title of several works in Sanskrit text attributed to the ancient sage (rishi) Agastya. Pancharatra 
One of the samhitas of the Pāñcarātrāgama is the Agastya Saṁhitā, which is about the worshipping of Rāma, Sītā, Lakṣmaṇa, and Hanumān, as laid down by Agastya. It is also known as Agastya-Sutīkṣṇa-Samvāda, as it is in the form of a conversation between the sages Sutīkṣṇa and Agastya. There are also other works titled Agastya Samhita among the Pancharatra texts, which are different from Sutīkṣṇa-Agastya-samvāda. Puranas 
Sections of certain Puranas believed to have been written by Agastya are called Agastya Samhita as well. Skanda Purana 
A section embedded in Skanda Purana is known as Agastya Samhita, and sometimes called the Sankara Samhita. It was probably composed in late medieval era, but before the 12th-century. It exists in many versions, and is structured as a dialogue between Skanda and Agastya. Scholars such as Moriz Winternitz state that the authenticity of the surviving version of this document is doubtful because Shaiva celebrities such as Skanda and Agastya teach Vaishnavism ideas and the bhakti (devotional worship) of Rama, mixed in with a tourist guide about Shiva temples in Varanasi and other parts of India. Garuda Purana 
Agastya Samhita is the name of one of the three sections of Garuda Purana which deals with the study of gems; the other two being the Brihaspati Samhita (Nitisara) and the Dhanvantari Samhita which is a study on material science, jurisprudence and medicine. Pseudohistorical claims 
In the early 20th century, Krishnaji Vinayak Vaze claimed to have found a manuscript of Agastya Samhita in a library in Ujjain, with the help of Damodar Tryambak Joshi, that allegedly described the process of making a dry electric battery. The battery is said to have been used for electroplating, and for producing hydrogen (and oxygen, through electrolysis of water) which was used to fly Vimanas. In 1927, Vaman Ramachandra Kokatnur, a chemist and inventor by profession, presented his papers based on this manuscript before the American Chemical Society. Amsu Bodhini Shastra by Pandit Subbaraya Shastry (ascribed to the sage Bharadvaja) mentions a text titled Shakti Tantra, said to have been written by Agastya, which describes 32 kinds of electricity and electronic machines and appliances. 