@article{Sosa1980,
author = {Sosa, R. and Kennell, J. and Klaus, M. and Robertson, S. and Urrutia, J.},
title= {The effect of a supportive companion on perinatal problems, length of labor, and mother-infant interactions},
year = {1980},
doi = {10.1056/NEJM198009113031101},
journal = {The New England Journal of Medicine},
volume = {303},
number = {11},
pages = {597--600},
}