Reference materials provide a good, working knowledge of key issues and sub-topics and provide ideas for other sources to explore. Beyond this list, you should know that all of the following types of materials can be helpful reference material for your research: almanacs, atlases, bibliographies, dictionaries, directories, encyclopedias, handbooks, and indexes.
For guidance on research methodology please consider:
Don't forget, the Research Data Services Team in Lehman Library is available to help with many aspects of the research data lifecycle including research data management, finding data, recommendation for cleaning and understanding data, mapping and visualizing your data.