Online reference resources include online dictionaries, encyclopedias, atlases, almanacs. These resources are helpful for reseach when you want to find information about topics, locate facts, and answer questions.
One of the most trusted sources of information on any topic used in research to provide background information.
The collection contains dictionaries, language reference, and subject reference works.
The Oxford handbook of environmental history by 
Dictionary of Ecology and Environment by 
Encyclopedia of Mammals by 