diff --git a/doc/smart_ptr/shared_ptr.adoc b/doc/smart_ptr/shared_ptr.adoc
index 64761dd..110e511 100644
--- a/doc/smart_ptr/shared_ptr.adoc
+++ b/doc/smart_ptr/shared_ptr.adoc
@@ -132,7 +132,6 @@ namespace boost {
     template<class Y> shared_ptr(shared_ptr<Y> && r) noexcept;
 
     template<class Y> shared_ptr(shared_ptr<Y> const & r, element_type * p) noexcept;
-
     template<class Y> shared_ptr(shared_ptr<Y> && r, element_type * p) noexcept;
 
     template<class Y> explicit shared_ptr(weak_ptr<Y> const & r);
@@ -373,7 +372,7 @@ template<class Y> shared_ptr(shared_ptr<Y> const & r, element_type * p) noexcept
 [none]
 * {blank}
 +
-Effects:: constructs a `shared_ptr` that shares ownership with `r` and stores `p`.
+Effects:: Copy-constructs a `shared_ptr` from `r`, while storing `p` instead.
 
 Postconditions:: `get() == p && use_count() == r.use_count()`.
 
diff --git a/doc/smart_ptr/weak_ptr.adoc b/doc/smart_ptr/weak_ptr.adoc
index d51eaa1..af2fee2 100644
--- a/doc/smart_ptr/weak_ptr.adoc
+++ b/doc/smart_ptr/weak_ptr.adoc
@@ -88,6 +88,10 @@ namespace boost {
 
     weak_ptr(weak_ptr && r) noexcept;
 
+    template<class Y> weak_ptr(shared_ptr<Y> const & r, element_type * p) noexcept;
+    template<class Y> weak_ptr(weak_ptr<Y> const & r, element_type * p) noexcept;
+    template<class Y> weak_ptr(weak_ptr<Y> && r, element_type * p) noexcept;
+
     ~weak_ptr() noexcept;
 
     weak_ptr & operator=(weak_ptr const & r) noexcept;
@@ -98,6 +102,8 @@ namespace boost {
     long use_count() const noexcept;
     bool expired() const noexcept;
 
+    bool empty() const noexcept;
+
     shared_ptr<T> lock() const noexcept;
 
     void reset() noexcept;
@@ -157,6 +163,21 @@ weak_ptr(weak_ptr && r) noexcept;
 Effects:: Constructs a `weak_ptr` that has the value `r` held.
 Postconditions:: `r` is empty.
 
+### aliasing constructors
+```
+template<class Y> weak_ptr(shared_ptr<Y> const & r, element_type * p) noexcept;
+```
+```
+template<class Y> weak_ptr(weak_ptr<Y> const & r, element_type * p) noexcept;
+```
+```
+template<class Y> weak_ptr(weak_ptr<Y> && r, element_type * p) noexcept;
+```
+Effects:: Constructs a `weak_ptr` from `r` as if by using the corresponding converting/copy/move constructor, but stores `p` instead.
+Postconditions:: `use_count() == r.use_count()`. When `!expired()`, `shared_ptr<T>(*this).get() == p`.
+
+NOTE: These constructors are an extension, not present in `std::weak_ptr`.
+
 ### destructor
 ```
 ~weak_ptr() noexcept;
@@ -204,6 +225,17 @@ bool expired() const noexcept;
 +
 Returns:: `use_count() == 0`.
 
+### empty
+```
+bool empty() const noexcept;
+```
+[none]
+* {blank}
++
+Returns:: `true` when `*this` is empty, `false` otherwise.
+
+NOTE: This function is an extension, not present in `std::weak_ptr`.
+
 ### lock
 ```
 shared_ptr<T> lock() const noexcept;