I have the continuity equation as shown here: imgur(dot)com/NRfMphl(dot)jpg

I need to find (deduce) this same equations with several considerations:
-Assuming taht E is very small and working with minority
-Assuming steady state conditions
-Assuming low injection conditions

I have never done Optoelectronics before, can someone point me to a book where I can find some guidance or to some page or something where I can find the deduction itself :)?

If someone just knows how to do it and can do it it would be awesome!! (please if you take the time to do it make it on paper and upload it somewhere as it is so difficult to understand things with web-text only)

Thank you very much!

https://i.imgur.com/NRfMphl.jpg