 The phenomenon has been studied in bibliometrics and scientometrics.A 2015 study published in the Proceedings of the National Academy of Sciences concluded, after looking at over 22 million scientific papers of the prior 100 years, that "sleeping beauties are common", and seen even in the works of the most famous scientists.In particular, that a paper on an aspect of quantum mechanics that was published in 1935 by Einstein, among other luminaries, did not receive widespread attention until 1994.