[alpha/Fe] vs. [Fe/H]. Filled blue circles are our data for NGC 6440, filled red triangles are NGC 6441 (Gratton et al. 2006, 2007), filled yellow triangles are Terzan 5 (Origlia et al. 2011, 2013), filled cyan triangles are Terzan 4 (Origlia & Rich 2004), filled dark green triangles are NGC 6553 (Tang et al. 2017), filled magenta triangles are HP1 (Barbuy et al. 2016), filled orange triangles are bulge field stars (Gonzalez et al. 2012), filled green squares are GCs from Pritzl et al. (2005), and filled gray triangles are halo and disk fields stars (Venn et al. 2004).