SQL Query Newbie Help

Given the two tables at the bottom of this email, I'm having trouble
coming up with a SQL statement that returns all rows in the
quality_control_reset table where there is only one row for the most
recent quality_control_range. Help?

Example:

In table quality_control_reset:

id | timestamp | qualitycontrolrange
---------------------------------------------
1 | 02/23/2006 | 20
2 | 02/23/2006 | 6
3 | 02/28/2006 | 18
4 | 03/01/2006 | 18
5 | 03/23/2006 | 12
6 | 03/23/2006 | 20

I want the results of the following from the query:

id | timestamp | qualitycontrolrange
---------------------------------------------
2 | 02/23/2006 | 6
4 | 03/01/2006 | 18
5 | 03/23/2006 | 12
6 | 03/23/2006 | 20

CREATE TABLE quality_control_reset
(
id int8 NOT NULL,
date timestamp,
qualitycontrolrange int8,
CONSTRAINT quality_control_reset_pkey PRIMARY KEY (id),
CONSTRAINT fk42a706efb62efa94 FOREIGN KEY (qualitycontrolrange)
REFERENCES quality_control_range (id) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION
)

CREATE TABLE quality_control_range (
id int8 NOT NULL,
code varchar(255),
CONSTRAINT quality_control_range_pkey PRIMARY KEY (id)
);