Hidayati, R., 		Tirta, I., & 		Dewi, Y.
(2014).
 The Efficiency of First (GEE1) and Second (GEE2) Order “Generalized Estimating Equations” for Longitudinal Data.
<em>Jurnal ILMU DASAR, 15</em>(1), 29-35.
doi:10.19184/jid.v15i1.553