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