Palestrina Pange lingua and falsobordone

Dear all

I know Palestrina wrote a polyphonic setting of the hymn Pange lingua, but I see that Sir Richard Terry gives a falsobordone version for alternating verses in his Music for Holy Week volume. I've searched for this in other sources but cannot find it. Anyone know where he gets it from? Or where one can find Palestrina falsobordones?

Many thanks.