Bismillahir Rahmanir Rahim
Assalaamu Alaikum wa Rahmatullahi wa Barakaatuh
Although, it is my suggestion that students invest in the purchase of authentic books I do realize that finances for some may not allow this at times. May Allah rectify the affairs of the believers and increase you benefits of knowledge allahummah aameen.
Here barakAllahu Feekunna is some downloads you can place on your laptop, tablet, or mobile phone if you so choose and Allah knows best