Jovic M, Sharma M, Rahajeng J, Caplan S. The early endosome: a busy sorting station for proteins at the crossroads. Histol Histopathol. 2010 January; 25(1): 99–112.http://www.ncbi.nlm.nih.gov/pubmed/19924646
Duna KW, McGraw TE, Maxfield FR. Iterative fractionation of recycling receptors from lysosomally destined ligands in an early sorting endosome. J Cell Biol. 1989 December 1; 109(6): 3303–3314. http://www.ncbi.nlm.nih.gov/pubmed/2600137/