Madhvacharya, also known as Anandatirtha, was a 13th-century philosopher and theologian who is considered to be the founder of the Dvaita Vedanta school of Hindu philosophy. He was a staunch proponent of the dualistic philosophy, which emphasizes the ultimate reality of two distinct and separate entities - the individual soul (jiva) and the supreme being (Brahman).

The main scriptures followed by Madhvacharya and his followers are the Vedas, the Upanishads, and the Bhagavad Gita. These texts form the basis of Dvaita Vedanta and are considered to be the ultimate authority on spiritual knowledge.

The Vedas, which are considered to be the most ancient scriptures in Hinduism, are a collection of hymns, rituals, and philosophical teachings. They are divided into four parts - Rig Veda, Yajur Veda, Sama Veda, and Atharva Veda. Madhvacharya believed that the Vedas were not composed by humans, but were revealed by the supreme being himself.

The Upanishads, which are also a part of the Vedas, are philosophical texts that explore the nature of reality and the relationship between the individual soul and the supreme being. Madhvacharya considered the Upanishads to be the most important scriptures for understanding the true nature of Brahman.

The Bhagavad Gita, which is a part of the epic Mahabharata, is a dialogue between Lord Krishna and Arjuna on the battlefield of Kurukshetra. Madhvacharya saw the Gita as a practical guide for living a righteous life and attaining liberation from the cycle of birth and death. He believed that the Gita's teachings were in line with the Dvaita philosophy and used it to support his arguments.

Apart from these three main scriptures, Madhvacharya also placed great importance on the teachings of the ancient sage Vyasa, the author of the Mahabharata. He believed that Vyasa's commentary on the Vedas, known as the Brahma Sutras, was essential for understanding the true meaning of the Vedas.

In addition to these texts, Madhvacharya also wrote several commentaries and philosophical treatises, such as the Anuvyakhyana and the Tattvavada Dipika, which further expounded on the principles of Dvaita Vedanta.

In conclusion, the main scriptures followed by Madhvacharya and his followers are the Vedas, the Upanishads, and the Bhagavad Gita. These texts are considered to be the ultimate source of spiritual knowledge and form the foundation of the Dvaita Vedanta philosophy. Madhvacharya's teachings continue to inspire and guide his followers in their pursuit of spiritual enlightenment.