how can we drive a 6 wire stepper motor by 4 wire driver like a4988

Hi.
Sorry for english writing .
I have about 10 stepper motor that they are 6 wire but my driver just have 4 wire to connect .
how can i use the steppers.
stepper motor: 1.8 deg / 1.7 a / TYPE 103H7121-1741 sanyo denki.

thanks for helping