An atlas is very useful when researching the location of towns, cities, countries or even continents. They will give you a detailed layout of where a place is and can be an important tool in subjects such as geography.
Dictionaries are often used in research and as references. Their main use is to concisely define a certain word or topic. They are also useful for finding out what something means if you are unfamiliar with the word.
Encyclopedias are frequently used as an excellent reference book. They cover a wide range of topics and go in to great detail about the subject. Some encyclopedias consist of only one letter per book as they are so detailed in their coverage.
Journals are usually a collection of academic work from an expert in the field.
Therefore they can provide a great reference point that is both detailed and highly respected.
A thesaurus may be a little more sparingly used than the other forms of reference books mentioned but it still has a valid use. A thesaurus can tell the researcher what other words are associated with the word they may be researching.
Reference books are vitally important in academia and they are used to back up any views and opinions written in an essay or dissertation. It is very hard to get a good mark in an essay without having great sources that have come from reference books.