diff --git a/README.md b/README.md
index ccf96c8..7459cc5 100644
--- a/README.md
+++ b/README.md
@@ -23,21 +23,22 @@ First, open environment and database
 
 	require 'sbdb'
 	Dir.mkdir 'newenv'  rescue Errno::EEXIST
-	env = SBDB::Env.new 'newenv', SBDB::CREATE
-	db = env.open SBDB::Btree, 'newdb.db', :flags => SBDB::CREATE
+	env = SBDB::Env.new 'newenv', SBDB::CREATE | SBDB::Env::INIT_TRANSACTION
+	db = env.btree 'newdb.db', :flags => SBDB::CREATE
 
 It works nearly like a Ruby-Hash:
 
 	db['key'] = 'value'
-	db['key']		# => 'value'
-	db.to_hash		# => {'key'=>'value'}
-	db.map {|k, v| [k, v].join ' => '}		# => ["key => value"]
-	db.count		# => 1
+	db['key']   # => 'value'
+	db.to_hash  # => {'key'=>'value'}
+	db.map {|k, v| "k => v" } # => ["key => value"]
+	db.count    # => 1
+	db.each {|k,v| puts "#{k}: #{v}" }
 
-SBDB::DB#each uses a SBDB::Cursor:
+`SBDB::DB#each` uses a `SBDB::Cursor`:
 
 	cursor = db.cursor
-	cursor.each {|k,v| puts "#{k}: ${v}" }
+	cursor.each {|k,v| puts "#{k}: #{v}" }
 
 **Don't forget to close everything, you've opened!**
 
@@ -47,10 +48,14 @@ SBDB::DB#each uses a SBDB::Cursor:
 
 But you can use a *lambda* to ensure to close everything:
 
-	SBDB::Env.new( 'newenv', SBDB::CREATE) do |env|
+	SBDB::Env.new( 'newenv', SBDB::CREATE | SBDB::Env::INIT_TRANSACTION) do |env|
 		env.open SBDB::Btree, 'newdb.db', :flags => SBDB::CREATE do |db|
 			db.to_hash
 		end
 	end
 
-SBDB::DB#to_hash creates a cursor and close it later.
+`SBDB::DB#to_hash` creates a cursor and close it later.
+
+Tip:
+
+	Signal.trap 'EXIT', env.method( :close)
diff --git a/Rakefile b/Rakefile
index 60d7e66..424d295 100644
--- a/Rakefile
+++ b/Rakefile
@@ -15,6 +15,7 @@ begin
     gem.files = %w[AUTHORS README.md VERSION lib/**/*.rb test/**/*.rb]
     gem.require_paths = %w[lib]
 		gem.add_dependency 'bdb'
+		gem.add_dependency 'ref'
   end
   Jeweler::GemcutterTasks.new
 rescue LoadError
diff --git a/VERSION b/VERSION
index 3f543b7..2cfabea 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.0.10.1
+0.0.11
diff --git a/lib/sbdb.rb b/lib/sbdb.rb
index d796a06..2b3ab6f 100644
--- a/lib/sbdb.rb
+++ b/lib/sbdb.rb
@@ -1,4 +1,5 @@
 require 'bdb'
+require 'ref'
 require 'sbdb/environment'
 require 'sbdb/db'
 require 'sbdb/cursor'