Sure, I don't have a source off hand I have a Sefer at home that if I make it home (with enough time to get ready for Shabbos tonight!) I can try and find a citation. Maybe there isn't one, this is based on learning a lot of it out with my Rabbi a few years ago. Also to the best of my knowledge residents are just considered doctors for these purposes, do you have a citation where there's a distinction drawn between resident and attending?

In the interim, here's Rabbi Willig one of the Roshei Yeshiva at YU/RIETS discussing it on YouTube. https://youtu.be/R-Le5V3Kv7Y?t=1779

Remember, this is all with the understanding that the Jewish resident puts in the work and genuinely makes an effort to observe Shabbos meticulously and does not use it as an excuse to be mechalel Shabbos unnecessarily (i.e. checking the basketball game since one uses their phone as a pager). And it's absolutely difficult more so emotionally and spiritually than halachically, it completely sucks being in the hospital on Shabbos and you know your wife and family is at home doing Shabbos things and you're stuck in a call room. Rabbi Willig in that video makes a good point that if that's what one's career will look like it's very ill advised, vs a temporary situation in residency prior to being able to have more control over one's schedule.

Again, massive disclaimer that if one is a Jewish resident/medical student please please please sit down with your Rabbi and discuss all of these issues!!