Don't compartmentalize paragraphs; they need purpose in themselves and together in a unit

notice how in this one you can consistently see the writers trying to determine what distinguishes the lonely from the lonely--TO DISTINGUISH is a research verb, active verb, etc., and trying to distinguish the lonely from the non-lonely is the organizing operation of the section--either way, the section is coherent

compare and contrast topoi--notice how BOTH paragraphs have a coherent purpose and flow together despite their being multiple studies

notice the difference between this and MLA in text citations; also notice the topoi of prevalence