Optical observations of GRB990907.
Published in 1999 by
E. Palazzi,
E. Pian,
N. Masetti,
F. Frontera 
,
P. M. Vreeswijk,
E. Rol,
H. Pedersen,
J. Hjorth,
J. van Paradijs,
C. Kouveliotou,
P. Leisy,
A. Pizzella,
E. Pompei,
R. Mennickent,
C. G. Tinney
and other authors.
,
P. M. Vreeswijk,
E. Rol,
H. Pedersen,
J. Hjorth,
J. van Paradijs,
C. Kouveliotou,
P. Leisy,
A. Pizzella,
E. Pompei,
R. Mennickent,
C. G. Tinney
and other authors.
