Research

Forbes : Smart Passive Income
Tin Conley
Forbes : 4 reasons why passive income is dangerous
Minamalist - there is no such thing as passive income
Live your Legend - Passive Income is a lie
Financial Mentor - Passive Income Hoax

bankrate - good video
investopia

Middle Income Trap - wiki
Income Gap

wiki: banks
world interest rate

residue income
printed books worldwide

ISBN
calculate # of books sold in amazon
wiki: royalty income

Patent, inventor

bank crisis