What are the implications for environmentally sound printmaking?
This kind of thesis question would probably involve a substantial amount of self-directed primary research; a thorough investigation of materials, an understanding of what aspects of printmaking have environmental implications (and what these precisely are), an investigation into the technical research and development by manufacturers to address the issues, case studies and so on. After considering exactly what kind of research you will need to do to answer your question you may decide that you are unable to take it on.
When developing a research question you need to work out all the different, relevant factors that will inform a convincing analysis. In other words you need to break your question or topic down into sub-questions. These sub-questions will then help you form the structure of the thesis.
All sources (written or unwritten) which were consulted during the course of the research should be in the Bibliography. It should include all material you have read and used during your thesis including books, articles, TV programmes, films, magazines, etc.