{HEAD ~ J} is one or more of Y, La, Ce, Eu, Th, U, and {TAIL ~ the remaining lanthanides} and j is from 0 to 3 
{ HEAD ~ J } is one or more of Y , La , Ce , Eu , Th , U , and { TAIL ~ the remaining lanthanides } and j is from 0 to 3
HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH