These mostly-practitioner-oriented guides and treatises can provide background information that will help put your issue into a broader context. Their citations to major primary authority can also serve as springboards for more in-depth research.
At USF most of these are available only in their online (Lexis, Westlaw, Bloomberg Law) versions.
Employment Law, 5th ed. by 
Americans with Disabilities Act Handbook, 5th ed by 
Fragomen on Immigration Fundamentals: A Guide to Law and Practice, 5th ed. by Ignacio searches broad descriptions of books. These are just a few examples of Ignacio keyword searches for legal topics:
"insider trading" law
"first amendment" religio*
"fundamental rights" united states
energy law
"family law" comparative
"discrimination in employment" "law and legislation"
"european union" law environment*
"european union" law employ*
"human rights" europ*
To further refine your Ignacio search results, select "Law Stacks" from the "Location" options on the left-hand side of the results screen.
To find scholarly books worldwide, try WorldCat.
WorldCat searches broad descriptions of books. Here are some examples of WorldCat keyword searches for books on legal topics:
"dispute resolution" indigenous
family leave law
police interrogation law
copyright comparative
"european union" and "intellectual property" and reform*
For even more flexible searching, try WorldCat Advanced Search.
In WorldCat Advanced Search, try "Subject" searches, which can be very thorough and powerful. (You can combine "Subject" searches with key words and can narrow your search in a number of ways.) Here are some examples of Subject searches:
"Intellectual property" "European Union countries"
Discrimination "European Union countries"
Find books by searching the full text of books using Google Books.
Because Google Books searches the full text, you can often get good results with more narrow, specific searches than would be useful in Doncore or WorldCat — searches such as:
"eminent domain" "public use" kelo
"digital rights management" "fair use"
"rational basis with bite"
"age discrimination"
"part time" work "comparative law"
"european union" law climate change carbon trading
"european union" privacy databases
With Advanced Search, you can search by author and title, and limit by publication date.