Did I miss some package so I can not compile read_write_mutex.hpp in boost?

[eric]

dear boost progamers: 


  when I tried to compile from my g++4.5.2 a simple file which include 
#include <boost/thread/read_write_mutex.hpp> 
------- 
root_at_eric-laptop:/home/eric/cppcookbook/ch12# g++ -lboost_thread
Example12-3.cpp 
Example12-3.cpp:3:45: fatal error: boost/thread/read_write_mutex.hpp: No
such file or directory 
compilation terminated. 
--------- 
and I check from / of my ubuntuLinux (10.04) with boost 1.46.1 
I can not find any file name as read_wirte_mutex.hpp 
--------- 
root_at_eric-laptop:/# find . | grep read_write_mutex.hpp 
root_at_eric-laptop:/# 


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and I can not digout from web how to make it compile under gcc/g++
plz help, Eric