Books about the same subject are assigned the same shelf mark number. You'll find the number on the spine of each book. The shelf mark numbers for selected topics are below:
Accounting: 657
Corporate Finance: 658.15
Economics : 330
Engineering: 620
Mathematics: 510
Physics : 530
Probabilities and Applied Mathematics: 519
Taxation: 336.12
Scholarly books can contain comprehensive accounts of research or scholarship, historical data, overviews, experts' views on themes/topics. They are particularly useful when you require background information and related research on a topic, when you want to put your topic in context, identify key theories and key researchers in a subject area.
What books are not good at is in researching current topics as it can take years to write and publish books. So whilst they can give you a good overview of a research area it is important to bring the research up to date by consulting other sources such as journals and newspapers.