Buick Century 2003 Owner's Manual page 50

The labels are located near the base of all three rear
seating positions.
1-44
To assist you in locating the
lower anchors for this child
restraint system, each
seating position with the
LATCH system has a label
on the seatback at each
lower anchor position.
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CAUTION:
If a LATCH-type child restraint isn't attached to
its anchorage points, the restraint won't be
able to protect the child correctly. In a crash,
the child could be seriously injured or killed.
Make sure that a LATCH-type child restraint is
properly installed using the anchorage points,
or use the vehicle's safety belts to secure the
restraint. See "Securing a Child Restraint
Designed for the LATCH System" or "Securing
a Child Restraint in a Rear Seat Position" in
the Index for information on how to secure a
child restraint in your vehicle.