If you want to study real and complex analysis, a classic text is W. Rudin's "[Real and complex analysis][1]". In fact pretty much anything by Rudin is excellent.

A more accessible title of Rudin is "[Principles of Mathematical Analysis][2]".

Another classic complex analysis book is by [Alfors][3], although the title by [Stewart and Tall][4], both called "Complex analysis", might be more accessible (and slightly more modern in its approach).

These are all introductory (1st year mathematics undergraduate) texts - for UK universities. 

Rudin's "Real and complex analysis" does contain advanced material, and is probably not suitable as an introductory text for an engineering student. Worth a look, just in case.


  [1]: http://www.amazon.com/Complex-Analysis-International-Applied-Mathematics/dp/0070542341
  [2]: http://www.amazon.com/Principles-Mathematical-Analysis-International-Mathematics/dp/0070856133/ref=pd_sim_b_8?ie=UTF8&refRID=0V5VR96GQNH113C1GXC1
  [3]: http://www.amazon.com/Complex-Analysis-Lars-Ahlfors/dp/0070006571/ref=sr_1_1?s=books&ie=UTF8&qid=1420151884&sr=1-1&keywords=alfors%20complex
  [4]: http://www.amazon.com/Complex-Analysis-Ian-Stewart/dp/0521287634/ref=sr_1_1?s=books&ie=UTF8&qid=1420151815&sr=1-1&keywords=complex%20analysis%20stewart