The changing length of PhDs.
Russo
Eugene
E
D004500:Education, Graduate / Q000191:economics / Q000592:standards*; D005060:Europe; D005257:Fellowships and Scholarships; D012108:Research Personnel / Q000191:economics / Q000193:education*; D012109:Research Support as Topic; D012586:Science / Q000191:economics / Q000193:education*; D013997:Time Factors; D014481:United States