Deep Learning, Ian Goodfellow, Yoshua Bengio, and Aaron Courville, 2016 (MIT Press) - This foundational textbook provides a comprehensive theoretical background on neural networks, including the structure and function of input layers in various architectures.
Neural Networks and Deep Learning, Michael A. Nielsen, 2015 (Determination Press) - An accessible online book that systematically introduces neural network concepts, explaining how input data is represented and fed into the network.