There is a lot of free resources on internet about machine learning, but some are better than others. If you want to read a thicker book and you are not scared of statistics:
- Christopher M. Bishop: Pattern Recognition and Machine Learning
If you want to read more about currently popular deep learning:
- Ian Goodfellow and Yoshua Bengio and Aaron Courville: Deep Learning
If you want to read the famous paper:
- Yann LeCun and Yoshua Bengio and Geoffrey Hinton: Deep Learning
Or if you want to know what is not precise in it:
- Jürgen Schmidhuber: Deep Learning Conspiracy
Or if you believe it's all connected as Albert Einstein once said, you might consider:
- Daphne Koller and Nir Friedman: Probabilistic Graphical Models