Good places to start your search for sources are your library and the internet. In all of the below cases, use search terms such as "education," "theme," "kipling" and "jungle book." Using "AND" between words will make the server search for both of the words together in the article. Using "OR" between words will let the server search for any article using either word but not necessarily both. Put quotes around phrases that include multiple words such as "jungle book" so the full phrase is searched for and not only part of it. For example (education AND theme AND kipling OR "jungle book").
Most libraries have research databases (either online or offline) of topics to search from. Please note that most of these databases are not available for individual use, but can only be used through an institution such as your library. Please visit your local or school library to gain access to these and to see what research databases they have available. Good research databases to use for literature include: Gale Virtual Reference Library, Thomson Gale's Literature Criticism Online, Literature Resource Center, or Ebsco. Your library may have many more or different databases to choose from.
Of course, while you're at your library, take a look through the catalog. Your library may have some physical copies of reviews or guides that talk about your topic. If you still can't find anything, talk to a librarian. They are very well trained in research and are there to do more than just check out your books.
If you aren't having any luck at your library, go online. Search engines like Google let you alter your searches so that you can limit results to only educational or scholarly resources. To do this, first type your search terms into the search box (education AND theme AND kipling OR jungle book). When the results page loads, click on the settings button (gear picture) to the far right. Select "advanced search." To limit your search to only education/academic related sites put ".edu" under the "Site or Domain" box. If you want to look through only scholarly articles, search with the same terms at scholar.google.com. This will only give you results from scholarly articles that can be used for academic sources.