Constructing Grounded Theory: A Practical Guide through Qualitative Analysis (Charmaz, 2006) – This book is brilliant, well written and incredibly comprehensive. If you ever considered learning about Grounded Theory, there is really no better book for you
If I was to choose one book to learn about research in general, it would be this one. It describes both qualitative and quantitative designs (here referred to as flexible and fixed designs, respectively) and all aspects related to planning and conducting a research study, such as a variety of methods, sampling techniques, theoretical considerations, etc. It is thick but it reads very well.
A real bible of research. Not the sort of book you want to read cover to cover (it has almost 500 pages!), but useful to search through subjects to find info on what you want.
The best book I’ve read on thesis writing. It gives advice about getting started with writing exercises, managing relationships with supervisors, free-writing as ideas generation, drafting etc. The salient feature of this book lies in the fact that it is greatly enhanced with the examples from the author’s longstanding practical experience with PhD students and supervisors as well as brilliat examples of different parts of a PhD thesis.