Deep Learning, Ian Goodfellow, Yoshua Bengio, and Aaron Courville, 2016 (MIT Press) - Covers the theoretical foundations of neural networks, including detailed explanations of forward propagation, various output units (linear, sigmoid, softmax), and their mathematical formulations.
Neural Networks and Deep Learning (Deep Learning Specialization, Course 1), Andrew Ng, Kian Katanforoosh, Younes Bensouda Mourri, 2017 (DeepLearning.AI) - Provides an accessible introduction to neural network fundamentals, clearly explaining forward propagation, activation functions, and the purpose of different output layers in a practical context.