The words of the Buddha were carried down through oral tradition after his death and later complied collections called suttas (Pali) or sutras (Sanskrit). These collections, plus the Vinaya Pitaka (monastic rules) and Abidhamma/Aabidharma (philosophical texts) compose the early Buddhist Canon (also known as the Pali Canon or Tripitaka)
Note! When searching for sutras in the catalogue knowing the Sanskrit and/or Pali name is useful
A non-exhaustive survey of books you can find at the History, Philosophy, and Newspaper Library
Pali Canon
In the Buddha Words (Selected texts of Pali Canon) Call No. BQ1192.E53 B63 2005
The Middle Length Discourses (Majjhima Nikāya) Call No. BQ1312.E5 N36 1995
The Numerical Discourses of the Buddha ( Anguttara Nikāya) Call No. BQ1342.E5 B63 2012
The Connected Discourses of the Buddha (Samyutta Nikāya) Call No. BQ1332.B63 E5 2000
The Long Discourses of the Buddha (Digha Nikāya) Call No. BQ1292.E53 W35 1995
The Therīgāthā Call No. BQ1452.E5 H35 2015
Some Mahayana Sūtras (later sūtras related to Mahayana Buddhism)
Lotus Sūtra (Saddharma Puṇḍarīka Sūtra) Call No: BQ2052.E5 W38 1993
The Heart Sūtra (Prajñāpāramitāhṛdaya) Call No. BQ1967.T35 2014
The Laṅkāvatāra Sūtra: Call No. BQ1722.E5 S89 1999
The Vimalakīrti Sūtra Call No. BQ2212.E5 W66 1997
These various sūtras are complied in different ways for each iteration of Buddhism in different regions. See Chinese Buddhist Canon, Korean Buddhist Canon, Tibetan Buddhist Canon etc.