When researching and analyzing literature it is important to understand the historical context of the writing or topic. In order to get the full picture, you will have to approach your research from more than one angle. For example, when researching William Blake's "The Chimney Sweeper" you will search for information on the poem using the search terms (1) "Chimney Sweeper" or (2) "Chimney Sweeper" AND "William Blake".
You would want to look up information on William Blake to understand the poet and his influences. In addition, you could look up information about the poet and the influence of the Industrial Revolution on his works.
In order to get a better understanding of this influence, you could search for historical information on the Industrial Revolution. This search would not include William Blake but will give your historical context that you can use when analyzing his works.