Lee, J., Springel, V., Pen, U.-L., & Lemson, G. (2008). Quantifying the cosmic web – I. The large-scale halo ellipticity–ellipticity and ellipticity–direction correlations. Monthly Notices of the Royal Astronomical Society, 389(3), 1266-1274. doi:10.1111/j.1365-2966.2008.13624.x.