What have other scholars or researchers written about the variables, research questions, and hypotheses?

Literature review for the following topic: “A study of urban agriculture in Washington, D.C. as a response to food equity”.
Hypothesis: An increase in urban agriculture would reduce Washington, D.C.’s food disparity.
Directions: What have other scholars or researchers written about the variables, research questions, and hypotheses? The review should be organized, relevant to the research questions and hypotheses.