Use systematic reading to find out some information about the resource, then read superficially to find out the overall theme.
At the beginning of the research project, you are not reading in-depth, you are doing inspectional reading to determine the best sources to use for your future research.
Begin with systematic reading.
This would include reading the back of the book or sometimes the inside cover to find out more about the book.
If you are reading an online article, read the abstract, which tells you the purpose of the research.
Other systematic reading tools include:
Determining the type of literature
Finding the publication date
Looking over the table of contents
Skimming the book or article to determine an overall theme
Would you like to understand more about levels of reading?