strings division instruction for specific desk in Italian

It is not a Dorico-related question. Are the following instructions correct for string division instruction?

  • leggio primo: should be played by the players at the first desk (= music stand)

  • leggio secondo: should be played by the players at the second desk

  • leggio terzo: should be played by the players at the third desk

  • leggio quarto: should be played by the players at the fourth desk

  • leggio quinto: should be played by the players at the fifth desk

  • leggio sesto: should be played by the players at the sixth desk

  • leggii quinti e sesti: should be played by the players at the fifth desk and sixth desk

I am not sure if the last one should be “leggio quinto e sesto” or “leggii quinti e sesti”.