The Mist by Stephen King (1980) — King's novella is set on Long Lake, and anyone who has seen the morning mist roll off the water in early summer will recognize the atmosphere immediately. It was adapted into a film in 2007. King had a long association with the Bridgton area.
The Story of a New Name and related books — E.B. White, who owned a vacation home on Long Lake, wrote about New England lake life with an affection that resonates here. His essays in One Man's Meat capture the quality of Maine summers better than most travel writing.
Yankee Magazine's New England — not a work of literature, but the magazine's decades of coverage of western Maine's lakes region offers good historical texture for understanding why Bridgton and its neighbors developed the way they did.