why use these 4 resistors?

who can tell me why these Rs in the attached circuit are used?
how to consider their resistance?
3X!

They are use to improve stability.

They can me calculated using G(v)min/Icq+100.

Yendori

why can these 4 resistors improve stability?
could you tell me sth. more detailed?
thanks very much!

I think it maybe for rejecting feedthrough from LO to RF.

to equalize currents trough different transistor pairs, because because LI and LQ levels can be differ from each other.