How can the letter "On Social Class and Happiness" by Margaret Cavendish be related to other academic sources?

I'm not sure what types of "academic" sources you're looking for, so I'll try to provide a wide variety of possibilities:
This work can be related to The Great Gatsby. In her letter, Cavendish conveys that the poor are often much happier than the wealthy. Jay Gatsby has more money than most could conceive of, but happiness eludes him because he can't have Daisy. In the end, his quest for Daisy costs him his life, despite all his riches.
In the poem "I'm Nobody! Who are you?" by Emily Dickinson, she conveys similar ideas. She would rather be a "nobody" (similar to Cavendish's ideas of the poor) than to be such a public (and presumably, wealthy) figure in society.
In the short story "The Necklace" by Guy de Maupassant, Mathilde borrows an expensive necklace from a friend and then loses it at a party. She goes in debt to replace it and finds out after a decade of hard labor in working to pay off her debt that the necklace was a fake. This short story pairs with Cavendish's letter by showing that even the seemingly wealthy portray illusions of grandeur, trying to impress others in visibly tangible ways, and that enjoying the simple beauties (like the flowers her husband suggests that she wear instead of an expensive necklace) leads to happiness.
Lorraine Hansberry's play A Raisin in the Sun shows how a family's fairly peaceful existence is filled with conflict when they suddenly have an extra $10,000 in their budget.