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