Yes, there is an …. online book and it’s pretty awesome!
I’d argue that one is enough.
It is very helpful to grasp the basics.
http://www.allaboutcircuits.com/
read a chapter every day & try to understand the subject.
Plus! You may also like Prof Walter Lewin’s lecture series on Physic 802 if you have an internet connection. Googling it will help you find it!