There are some legal ways to read books for free, but not forever. There are two most popular services for a monthly based subscribtion for all the books. They give a first month for free (with easy cancellation anytime), so that you can easily read as much as you want and pay for subscription in case you liked it.

Kindle costs 10$, while Scribd costs 8$ per month.

Kindle Unlimited

Scribd

Also, Ukrainian literature can be found on NashFormat, and russian-translated business literature can be downloaded on Flibusta.