<Tr> <Td> Thomas Jefferson </Td> <Td> </Td> <Td> n / a </Td> </Tr> <Tr> <Td> James Madison </Td> <Td> </Td> <Td> n / a </Td> </Tr> <Tr> <Td> James Monroe </Td> <Td> </Td> <Td> n / a </Td> </Tr> <Tr> <Td> John Quincy Adams </Td> <Td> </Td> <Td> n / a </Td> </Tr>

What is the source of authority in the united states government