Torres, Nancy, et al. “Antibiotic Resistance of Streptococcus Pneumoniae Among Healthy Nasopharyngeal Carriers in Seven Regions of Peru”. Revista Peruana De Medicina Experimental Y Salud Pública, vol. 30, no. 4, Mar. 2014, https://doi.org/10.17843/rpmesp.2013.304.235.