http://decsai.ugr.es/~smc/uai99/uaireg.html
That web page also contains information about how to reserve a hotel room.
IMPORTANT:
* It is critical that you request a hotel room by April 26th. Otherwise, you
might not be able to reserve a room in Stockholm for the conference period.
(For details, please see the web page mentioned above.)
* Early registration for UAI'99 ends on May 31st.