Best instruments for "years of schooling"/"education" As an answer to question “Seminal papers that later were proven to contain errors”, @snoram mentioned Angrist and Krueger (1991), and there use of quarter of birth as an (exogenous) instrument for education.

@snoram illustrates using (Buckles and Hungerman, 2013) how quarter of birth is in fact correlated with important characteristics of the mother. 

In a comment, @snoram write:


  “For the record I think Angrist and Krueger's work is amazing, but
  today we know better than to use quarter of birth (in the us at least
  and for this purpose) as an instrument. Science advances.”


My question : which variables are know to be better than quarter of birth as instruments for, say, “years of schooling” (or more generally “education”)?
Check out
Estimating the Return to Schooling: Progress on Some Persistent Econometric
Problems by David Card (2001) ECA

I know distance from school has been used in the past as an IV..although it has been criticized.