Deep Learning, Ian Goodfellow, Yoshua Bengio, and Aaron Courville, 2016 (MIT Press) - A comprehensive and authoritative textbook covering the theoretical and practical aspects of deep learning, including unsupervised learning and autoencoders.
The Elements of Statistical Learning: Data Mining, Inference, and Prediction, Trevor Hastie, Robert Tibshirani, and Jerome Friedman, 2009 (Springer) - A foundational textbook providing a statistical perspective on machine learning algorithms, covering various unsupervised learning methods such as clustering and dimensionality reduction.
Reducing the Dimensionality of Data with Neural Networks, Geoffrey E. Hinton, Ruslan R. Salakhutdinov, 2006Science, Vol. 313 (American Association for the Advancement of Science)DOI: 10.1126/science.1127647 - A seminal paper demonstrating the effectiveness of deep autoencoders for nonlinear dimensionality reduction, which was crucial for the resurgence of deep learning.