The search, whether simple or advanced, is a means to locate a work, in agreement with the parameters that we have selected or the terms that have been employed. As such, it cannot be used to search the content of works. Nonetheless, depending on the digitization that each library has performed, once you select the work, it is possible that you may be able to do this kind of search.
Once you have made a search, click on the title to access the work in question and the details of the entry will be shown. If you wish to continue and see the content you will have to click on the button that says Access, or go back to examine a different item or to make a new search. In the majority of cases, when pressing Access, the system will directly take you to the text. However, certain libraries do not allow this function, and in these cases you will be taken to the library where the work is kept so that you can access the work or apply for a download.
You should bear in mind that not all libraries have conducted their digitalization in the same way, nor will the programs used be the same. As such, you may not be able to see preview information, or you may have to enter the third-party website and request it.