Can anyone help me locate Crossfire?!?

[summeral@benji.Colorado.EDU (Summerall Thomas G)]

I used to have a gam called Crossfire for the apple II plus, and e.  I think
it was made by Sirius.  There was a grid of squares and ships moved between 
the squares shooting at your ship.  You could move using four keys and fire
using four other keys.  I would love to buy this from someone, unless it has 
reverted to the public domain.

Anyone have any idea where I might find this game?

Thanks,

Tom Summerall