diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,7 @@
+## 0.5.1.1
+
+- Update documentation.
+
 ## 0.5.1.0
 
 - Add the arrow combinator module and its unit-test cases.
diff --git a/relational-query.cabal b/relational-query.cabal
--- a/relational-query.cabal
+++ b/relational-query.cabal
@@ -1,5 +1,5 @@
 name:                relational-query
-version:             0.5.1.0
+version:             0.5.1.1
 synopsis:            Typeful, Modular, Relational, algebraic query engine
 description:         This package contiains typeful relation structure and
                      relational-algebraic query building DSL which can
diff --git a/src/Database/Relational/Query/Derives.hs b/src/Database/Relational/Query/Derives.hs
--- a/src/Database/Relational/Query/Derives.hs
+++ b/src/Database/Relational/Query/Derives.hs
@@ -70,7 +70,7 @@
          -> Relation p a    -- ^ Result restricted 'Relation'
 primary' =  specifiedKey . projectionKey
 
--- | Query restricted with infered primary key.
+-- | Query restricted with inferred primary key.
 primary :: HasConstraintKey Primary a p
         => Relation () a -- ^ 'Relation' to add restriction.
         -> Relation p a  -- ^ Result restricted 'Relation'
@@ -94,13 +94,13 @@
                       -> KeyUpdate p r -- ^ Result typed 'Update'
 updateByConstraintKey table' = typedKeyUpdate table' . Constraint.projectionKey
 
--- | Typed 'KeyUpdate' using infered primary key.
+-- | Typed 'KeyUpdate' using inferred primary key.
 primaryUpdate :: (HasConstraintKey Primary r p)
               => Table r       -- ^ 'Table' to update
               -> KeyUpdate p r -- ^ Result typed 'Update'
 primaryUpdate table' = updateByConstraintKey table' (uniqueKey constraintKey)
 
--- | 'UniqueRelation' infered from table.
+-- | 'UniqueRelation' inferred from table.
 derivedUniqueRelation :: TableDerivable r
                       => Key Unique r k        -- ^ Unique key proof object which record type is 'a' and key type is 'p'.
                       -> Projection c k        -- ^ Unique key value to specify.
diff --git a/src/Database/Relational/Query/Monad/Class.hs b/src/Database/Relational/Query/Monad/Class.hs
--- a/src/Database/Relational/Query/Monad/Class.hs
+++ b/src/Database/Relational/Query/Monad/Class.hs
@@ -45,7 +45,7 @@
   -- | Add restriction to last join.
   restrictJoin :: Projection Flat (Maybe Bool) -- ^ 'Projection' which represent restriction
                -> m ()                         -- ^ Restricted query context
-  -- | Unsafely join subquery with this query.
+  -- | Unsafely join sub-query with this query.
   unsafeSubQuery :: NodeAttr              -- ^ Attribute maybe or just
                  -> Qualified SubQuery    -- ^ 'SubQuery' to join
                  -> m (Projection Flat r) -- ^ Result joined context and 'SubQuery' result projection.
diff --git a/src/Database/Relational/Query/Monad/Trans/Join.hs b/src/Database/Relational/Query/Monad/Trans/Join.hs
--- a/src/Database/Relational/Query/Monad/Trans/Join.hs
+++ b/src/Database/Relational/Query/Monad/Trans/Join.hs
@@ -66,7 +66,7 @@
   restrictJoin       = updateJoinRestriction . expr
   unsafeSubQuery     = unsafeSubQueryWithAttr
 
--- | Unsafely join subquery with this query.
+-- | Unsafely join sub-query with this query.
 unsafeSubQueryWithAttr :: Monad q
                        => NodeAttr                        -- ^ Attribute maybe or just
                        -> Qualified SubQuery              -- ^ 'SubQuery' to join
diff --git a/src/Database/Relational/Query/Pi/Unsafe.hs b/src/Database/Relational/Query/Pi/Unsafe.hs
--- a/src/Database/Relational/Query/Pi/Unsafe.hs
+++ b/src/Database/Relational/Query/Pi/Unsafe.hs
@@ -124,7 +124,7 @@
 definePi' pw i = Pi (Leftest i) pw
 
 -- | Unsafely define projection path from type 'r0' into type 'r1'.
---   Use infered 'PersistableRecordWidth'.
+--   Use inferred 'PersistableRecordWidth'.
 definePi :: PersistableWidth r1
          => Int      -- ^ Index of flat SQL value list
          -> Pi r0 r1 -- ^ Result projection path
@@ -137,7 +137,7 @@
 defineDirectPi' pw is = Pi (Map is) pw
 
 -- | Unsafely define projection path from type 'r0' into type 'r1'.
---   Use infered 'PersistableRecordWidth'.
+--   Use inferred 'PersistableRecordWidth'.
 defineDirectPi :: PersistableWidth r1
                => [Int]    -- ^ Indexes of flat SQL value list
                -> Pi r0 r1 -- ^ Result projection path
diff --git a/src/Database/Relational/Query/Projectable.hs b/src/Database/Relational/Query/Projectable.hs
--- a/src/Database/Relational/Query/Projectable.hs
+++ b/src/Database/Relational/Query/Projectable.hs
@@ -566,7 +566,7 @@
   -- | Method like 'fmap'.
   (|$|) :: ProductConstructor (a -> b) => (a -> b) -> p a -> p b
 
--- | Same as '|$|' other than using infered record constructor.
+-- | Same as '|$|' other than using inferred record constructor.
 ipfmap :: (ProjectableFunctor p, ProductConstructor (a -> b))
        => p a -> p b
 ipfmap =  (|$|) productConstructor
diff --git a/src/Database/Relational/Query/Projection.hs b/src/Database/Relational/Query/Projection.hs
--- a/src/Database/Relational/Query/Projection.hs
+++ b/src/Database/Relational/Query/Projection.hs
@@ -90,11 +90,11 @@
                   -> Projection c r -- ^ Result 'Projection'
 unsafeFromColumns =  typedProjection . untypedProjectionFromColumns
 
--- | Unsafely generate  'Projection' from qualified (joined) subquery.
+-- | Unsafely generate  'Projection' from qualified (joined) sub-query.
 unsafeFromQualifiedSubQuery :: Qualified SubQuery -> Projection c t
 unsafeFromQualifiedSubQuery =  typedProjection . untypedProjectionFromJoinedSubQuery
 
--- | Unsafely generate 'Projection' from scalar subquery.
+-- | Unsafely generate 'Projection' from scalar sub-query.
 unsafeFromScalarSubQuery :: SubQuery -> Projection c t
 unsafeFromScalarSubQuery =  typedProjection . untypedProjectionFromScalarSubQuery
 
diff --git a/src/Database/Relational/Query/Relation.hs b/src/Database/Relational/Query/Relation.hs
--- a/src/Database/Relational/Query/Relation.hs
+++ b/src/Database/Relational/Query/Relation.hs
@@ -118,19 +118,19 @@
     unsafeSubQuery attr q
   -- d (Relation q) = unsafeMergeAnotherQuery attr q
 
--- | Join subquery with place-holder parameter 'p'. query result is not 'Maybe'.
+-- | Join sub-query with place-holder parameter 'p'. query result is not 'Maybe'.
 query' :: (MonadQualify ConfigureQuery m, MonadQuery m)
        => Relation p r
        -> m (PlaceHolders p, Projection Flat r)
 query' =  queryWithAttr Just'
 
--- | Join subquery. Query result is not 'Maybe'.
+-- | Join sub-query. Query result is not 'Maybe'.
 query :: (MonadQualify ConfigureQuery m, MonadQuery m)
       => Relation () r
       -> m (Projection Flat r)
 query =  fmap snd . query'
 
--- | Join subquery with place-holder parameter 'p'. Query result is 'Maybe'.
+-- | Join sub-query with place-holder parameter 'p'. Query result is 'Maybe'.
 queryMaybe' :: (MonadQualify ConfigureQuery m, MonadQuery m)
             => Relation p r
             -> m (PlaceHolders p, Projection Flat (Maybe r))
@@ -138,7 +138,18 @@
   (ph, pj) <- queryWithAttr Maybe pr
   return (ph, Projection.just pj)
 
--- | Join subquery. Query result is 'Maybe'.
+-- | Join sub-query. Query result is 'Maybe'.
+--   The combinations of 'query' and 'queryMaybe' express
+--   inner joins, left outer joins, right outer joins, and full outer joins.
+--   Here is an example of a right outer join:
+--
+-- @
+--   outerJoin = relation $ do
+--     e <- queryMaybe employee
+--     d <- query department
+--     on $ e ?! E.deptId' .=. just (d ! D.deptId')
+--     return $ (,) |$| e |*| d
+-- @
 queryMaybe :: (MonadQualify ConfigureQuery m, MonadQuery m)
            => Relation () r
            -> m (Projection Flat (Maybe r))
@@ -149,7 +160,7 @@
               . fmap Projection.unsafeListFromSubQuery
               . subQueryQualifyFromRelation
 
--- | List subQuery, for /IN/ and /EXIST/ with place-holder parameter 'p'.
+-- | List sub-query, for /IN/ and /EXIST/ with place-holder parameter 'p'.
 queryList' :: MonadQualify ConfigureQuery m
            => Relation p r
            -> m (PlaceHolders p, ListProjection (Projection c) r)
@@ -157,7 +168,7 @@
   ql <- queryList0 rel
   return (placeHoldersFromRelation rel, ql)
 
--- | List subQuery, for /IN/ and /EXIST/.
+-- | List sub-query, for /IN/ and /EXIST/.
 queryList :: MonadQualify ConfigureQuery m
           => Relation () r
           -> m (ListProjection (Projection c) r)
@@ -410,13 +421,13 @@
       qualifyQuery sq
     Projection.unsafeChangeContext <$> unsafeSubQuery attr q
 
--- | Join unique subquery with place-holder parameter 'p'.
+-- | Join unique sub-query with place-holder parameter 'p'.
 uniqueQuery' :: MonadQualifyUnique ConfigureQuery m
              => UniqueRelation p c r
              -> m (PlaceHolders p, Projection c r)
 uniqueQuery' = uniqueQueryWithAttr Just'
 
--- | Join unique subquery with place-holder parameter 'p'. Query result is 'Maybe'.
+-- | Join unique sub-query with place-holder parameter 'p'. Query result is 'Maybe'.
 uniqueQueryMaybe' :: MonadQualifyUnique ConfigureQuery m
                   => UniqueRelation p c r
                   -> m (PlaceHolders p, Projection c (Maybe r))
@@ -437,7 +448,7 @@
   (ph, a) <- query' rel
   return (ph, ag $ a ! k)
 
--- | Scalar subQuery with place-holder parameter 'p'.
+-- | Scalar sub-query with place-holder parameter 'p'.
 queryScalar' :: (MonadQualify ConfigureQuery m, ScalarDegree r)
              => UniqueRelation p c r
              -> m (PlaceHolders p, Projection c (Maybe r))
@@ -445,7 +456,7 @@
   unsafeAddPlaceHolders . liftQualify $
   Projection.unsafeFromScalarSubQuery <$> subQueryQualifyFromRelation (unUnique ur)
 
--- | Scalar subQuery.
+-- | Scalar sub-query.
 queryScalar :: (MonadQualify ConfigureQuery m, ScalarDegree r)
             => UniqueRelation () c r
             -> m (Projection c (Maybe r))
diff --git a/src/Database/Relational/Query/Sub.hs b/src/Database/Relational/Query/Sub.hs
--- a/src/Database/Relational/Query/Sub.hs
+++ b/src/Database/Relational/Query/Sub.hs
@@ -170,7 +170,7 @@
 
 -- | SQL string for nested-query and toplevel-SQL.
 toSQLs :: SubQuery
-       -> (StringSQL, StringSQL) -- ^ subquery SQL and top-level SQL
+       -> (StringSQL, StringSQL) -- ^ sub-query SQL and top-level SQL
 toSQLs =  d  where
   d (Table u)               = (stringSQL $ Table.name' u, fromTableToSQL u)
   d (Bin (BinOp (op, da)) l r) = (SQL.paren q, q)  where
diff --git a/src/Database/Relational/Query/TH.hs b/src/Database/Relational/Query/TH.hs
--- a/src/Database/Relational/Query/TH.hs
+++ b/src/Database/Relational/Query/TH.hs
@@ -194,7 +194,7 @@
         derivedTable = Table.table $(stringE table) $(listE $ map stringE columns)
     |]
 
--- | Template to define infered entries from table type.
+-- | Template to define inferred entries from table type.
 defineTableDerivations :: VarName -- ^ Table declaration variable name
                        -> VarName -- ^ Relation declaration variable name
                        -> VarName -- ^ Insert statement declaration variable name
diff --git a/src/Database/Relational/Query/Type.hs b/src/Database/Relational/Query/Type.hs
--- a/src/Database/Relational/Query/Type.hs
+++ b/src/Database/Relational/Query/Type.hs
@@ -191,7 +191,7 @@
 typedInsert :: Table r -> Pi r r' -> Insert r'
 typedInsert =  typedInsert' defaultConfig
 
--- | Table type infered 'Insert'.
+-- | Table type inferred 'Insert'.
 derivedInsert :: TableDerivable r => Pi r r' -> Insert r'
 derivedInsert =  typedInsert derivedTable
 
@@ -218,7 +218,7 @@
 typedInsertQuery :: Table r -> Pi r r' -> Relation p r' -> InsertQuery p
 typedInsertQuery =  typedInsertQuery' defaultConfig
 
--- | Table type infered 'InsertQuery'.
+-- | Table type inferred 'InsertQuery'.
 derivedInsertQuery :: TableDerivable r => Pi r r' -> Relation p r' -> InsertQuery p
 derivedInsertQuery =  typedInsertQuery derivedTable