The combination 3 wherein {HEAD ~ said rare earth material} is selected from {TAIL ~ the group} consisting of yttrium, lanthanum and hafnium 
is selected from
The combination 3 wherein { HEAD ~ said rare earth material } is selected from { TAIL ~ the group } consisting of yttrium , lanthanum and hafnium
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH