A bit on the science of (language) learning

References to papers:

Vocabulary range (frequency of 1000 words in Spanish)
Davies, M. (2005). Vocabulary range and text coverage: Insights from the forthcoming Routledge frequency dictionary of Spanish. In Selected proceedings of the 7th Hispanic Linguistics Symposium (pp. 106-115). Somerville, MA: Cascadilla.
https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=11510c24eed4c4db4d98b8becc996058630b079e

Incredibly detailed paper about Spaced Repetition and the search for the fastest learning!
https://gwern.net/spaced-repetition