H. Pietila

Burrau's three-body problem in the post-Newtonian approximation

S. Mikkola, M. Valtonen, H. Pietila, 1995 .

PROBING THE JET IN THE BINARY BLACK HOLE MODEL OF THE QUASAR OJ287

H. Lehto, M. Valtonen, H. Pietila, 1999 .