Long Short-Term Memory, Sepp Hochreiter and Jürgen Schmidhuber, 1997Neural Computation, Vol. 9 (MIT Press)DOI: 10.1162/neco.1997.9.8.1735 - Introduces the Long Short-Term Memory (LSTM) architecture, detailing the initial design of the memory cell and its gating mechanisms.
Deep Learning, Ian Goodfellow, Yoshua Bengio, and Aaron Courville, 2016 (MIT Press) - Offers a comprehensive treatment of deep learning, including recurrent neural networks and the LSTM architecture with its gating system.
Understanding LSTMs, Christopher Olah, 2015 - Provides a clear, visual explanation of LSTM networks, making the functions of each gate, including the input gate, easily understandable.