Yadav, R., Upadhyaya, L.N., Singh, H.P. and Chatterjee, S. 2013. A chain ratio exponential type estimator in two-phase sampling using auxiliary information. Statistica. 73, 2 (Jan. 2013), 221–234. DOI:https://doi.org/10.6092/issn.1973-2201/4133.