Which president pardoned Richard Nixon?

Which constitutional amendment, ratified in 1951, limits presidents to two elected terms? Which is the only president to resign from office? Which scandal led to Richard Nixon's resignation? Which president was never elected as either president or vice president? Which four presidents were assassinated in office? Who assassinated Abraham Lincoln? In which theater was Abraham Lincoln shot in 1865? In which city was John F. Kennedy assassinated in 1963?