TY  - RPRT
TI  - hi_class background evolution, initial conditions and approximation schemes
AU  - Bellini, Emilio
AU  - Sawicki, Ignacy
AU  - Zumalacárregui, Miguel
PY  - 2020
DO  - 10.1088/1475-7516/2020/02/008
UR  - https://www.osti.gov/biblio/1603623
ID  - 1603623
ER  -