00274nam a2200121Ia 4500082002000000100002300020245002200043260002900065300001500094490003300109500000500142700000500147  a515.24bH474.RT  aHelgason, Sigurdur  aRadon transformb  aBostonbBirkhauserc1980  avii, 192p.  aProgress in Mathematics v 5  a  a