The WorldCat Research Station is the essential tool for finding books, eBooks, DVDs, etc. available in and through the Zondervan Library.
Field prefixes in WorldCat:
yr: range of years -- e.g., 1980..2016
Here's a search on (ti:sustainab* AND agricultur*) OR (su:sustainab* AND agricultur*) ["'sustainable agriculture" or variant in a title or in a subject heading] and limited to resources available through the Zondervan Library.
Worldcat is also a very useful resource for generating interlibrary loan requests for books or articles:
Find citation/entry for item (e.g., book or article) --> Search by title (ti: prefix) in WorldCat --> Request Item through Interlibrary Loan. See Google Scholar to WorldCat to ILLiad video
Google Books: Explores the contents of millions of digitized books.
Select "Search Tools" > Any Books > "Preview available" to discover fully "digitized" books.
To search within specific books. See this brief video: limit the search to "Preview" books.
“Get this book in print” --> “Find in a Library” will take you to WorldCat.org where you can request a book via interlibrary when not available in Zondervan Library.
See this video on going from Google Books to finding the book in WorldCat in "print" format that can be requested through interlibrary loan.
It may not be easy to find reports or "gray literature" on some topics. Three key tools are WorldCat Research Station, Google Scholar and perhaps most effective a Google Web search.
In WorldCat Research Station search your topic, then LIMIT by FORMAT limiting to "Archival material" and "Internet Resource".
What you find will often have a direct link (e.g., View Now) to the online resource.
In Google Scholar and Google Web, identify "gray literature" by noting the absence of a journal title, publication source and the use of "report OR paper OR briefing" in your search strategy.
In a Google Web search, go to Advanced Search and try limiting your topic to .org in the Site or Domain: field. You may also want to use ".pdf" in the search box with your search terms.
Another resource of potential value for "white papers": the Congressional Research Service (URL is to a Google Search "Congressional Research Service" to which you can add search terms.)
Here is a search example on "sustainable agriculture".