At the time of this pandemic, many individuals, publishing institutions, and companies have been generous enough to help people. Springer is one of them. The publishing company with many textbooks that are used and recommended at many academic and professional institutions.
They have been generous enough to give everyone who is interested the chance to download 409 of its scientific books.
65 of those books are related to Machine Learning and Data Science. You can each of them at this link.
If you want to view the full list, you can go at this page.
In case you are interested in downloading many of such books without having to do it individually for each title, there is already a GitHub repository that allows you to download batches of book.
You can use it to download all the books, or filter them based on the language, for example, download only English books, or German books.
You can also download books based on book categories, such as Computer Science.
For more information regarding this, please refer to the GitHub repository itself, where you can find information in more details.
I hope this helps you get more knowledge in the field of your liking and that you practice that knowledge to pay it back to society.