Student or Learner
That was clearly the doctor's mistake. I want to let him know
1) so that it won't happen again in the future
2) for the future
3) for future references
the idea is in 1). Can I say it shortly as in 2) and 3)?
If you change "references" to "reference", #3 is OK. The other two are also OK.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.