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
PRIMARYKEY (id)
 
);