主題:外部性
https://docs.google.com/viewer?a=v&q=cache:z224ZviMV4QJ:web.nutn.edu.tw/gac230/post/37-1/%25EF%25BC%2597%25E5%259C%258B%25E5%25AE%25B6%25E4%25BB%258B%25E5%2585%25A5%25E6%2595%2599%25E8%2582%25B2%25E7%259A%2584%25E5%2590%2588%25E7%2590%2586%25E5%259F%25BA%25E7%25A4%258E.pdf+&hl=zh-TW&pid=bl&srcid=ADGEESjni10w3hvCxFrE4NzOuWHmI-mV-UbAsyGu-rQiwUgHN1z8Gqn3SmQ8tLxJkYY8cb9zCfJNrYN5l4TBaQZouNxV6b2J0JOmUX3hBJc_JoyW6I9IUlxGF7pxkqWBiX9DAUkHXujh&sig=AHIEtbTWysV6UXyDaPLqFsYXHQhlgBy32g