Walker, CL; Rudan, I; Liu, L; Nair, H; Theodoratou, E; Bhutta, ZA; O'Brien, KL; Campbell, H et al. (Apr 20, 2013). «Global burden of childhood pneumonia and diarrhoea.». Lancet381 (9875): 1405-16. PMID23582727. doi:10.1016/s0140-6736(13)60222-6.Se sugiere usar |número-autores= (ayuda)
Graham, JP; Polizzotto, ML (mayo de 2013). «Pit latrines and their impacts on groundwater quality: a systematic review.». Environmental health perspectives121 (5): 521-30. PMID23518813. doi:10.1289/ehp.1206028.
Walker, CL; Rudan, I; Liu, L; Nair, H; Theodoratou, E; Bhutta, ZA; O'Brien, KL; Campbell, H et al. (Apr 20, 2013). «Global burden of childhood pneumonia and diarrhoea.». Lancet381 (9875): 1405-16. PMID23582727. doi:10.1016/s0140-6736(13)60222-6.Se sugiere usar |número-autores= (ayuda)
Graham, JP; Polizzotto, ML (mayo de 2013). «Pit latrines and their impacts on groundwater quality: a systematic review.». Environmental health perspectives121 (5): 521-30. PMID23518813. doi:10.1289/ehp.1206028.