diff --git a/phlex/core/declared_unfold.cpp b/phlex/core/declared_unfold.cpp
index 298ea7ce..615ace95 100644
--- a/phlex/core/declared_unfold.cpp
+++ b/phlex/core/declared_unfold.cpp
@@ -8,10 +8,10 @@
 namespace phlex::experimental {
 
   generator::generator(product_store_const_ptr const& parent,
-                       std::string const& node_name,
+                       std::string node_name,
                        std::string const& new_level_name) :
     parent_{std::const_pointer_cast<product_store>(parent)},
-    node_name_{node_name},
+    node_name_{std::move(node_name)},
     new_level_name_{new_level_name}
   {
   }
diff --git a/phlex/core/declared_unfold.hpp b/phlex/core/declared_unfold.hpp
index 201f56ab..7b0477ba 100644
--- a/phlex/core/declared_unfold.hpp
+++ b/phlex/core/declared_unfold.hpp
@@ -36,7 +36,7 @@ namespace phlex::experimental {
   class generator {
   public:
     explicit generator(product_store_const_ptr const& parent,
-                       std::string const& node_name,
+                       std::string node_name,
                        std::string const& new_level_name);
     product_store_const_ptr flush_store() const;
 
@@ -48,7 +48,7 @@ namespace phlex::experimental {
   private:
     product_store_const_ptr make_child(std::size_t i, products new_products);
     product_store_ptr parent_;
-    std::string_view node_name_;
+    std::string node_name_;
     std::string const& new_level_name_;
     std::map<level_id::hash_type, std::size_t> child_counts_;
   };
diff --git a/phlex/model/product_store.cpp b/phlex/model/product_store.cpp
index a5be9780..22823a49 100644
--- a/phlex/model/product_store.cpp
+++ b/phlex/model/product_store.cpp
@@ -8,13 +8,13 @@ namespace phlex::experimental {
 
   product_store::product_store(product_store_const_ptr parent,
                                level_id_ptr id,
-                               std::string_view source,
+                               std::string source,
                                stage processing_stage,
                                products new_products) :
     parent_{std::move(parent)},
     products_{std::move(new_products)},
     id_{std::move(id)},
-    source_{source},
+    source_{std::move(source)},
     stage_{processing_stage}
   {
   }
@@ -22,12 +22,12 @@ namespace phlex::experimental {
   product_store::product_store(product_store_const_ptr parent,
                                std::size_t new_level_number,
                                std::string const& new_level_name,
-                               std::string_view source,
+                               std::string source,
                                products new_products) :
     parent_{parent},
     products_{std::move(new_products)},
     id_{parent->id()->make_child(new_level_number, new_level_name)},
-    source_{source},
+    source_{std::move(source)},
     stage_{stage::process}
   {
   }
@@ -35,18 +35,22 @@ namespace phlex::experimental {
   product_store::product_store(product_store_const_ptr parent,
                                std::size_t new_level_number,
                                std::string const& new_level_name,
-                               std::string_view source,
+                               std::string source,
                                stage processing_stage) :
     parent_{parent},
     id_{parent->id()->make_child(new_level_number, new_level_name)},
-    source_{source},
+    source_{std::move(source)},
     stage_{processing_stage}
   {
   }
 
   product_store::~product_store() = default;
 
-  product_store_ptr product_store::base() { return product_store_ptr{new product_store}; }
+  product_store_ptr product_store::base(std::string base_name)
+  {
+    return product_store_ptr{
+      new product_store{nullptr, level_id::base_ptr(), std::move(base_name)}};
+  }
 
   product_store_const_ptr product_store::parent(std::string const& level_name) const noexcept
   {
@@ -77,33 +81,36 @@ namespace phlex::experimental {
     return product_store_ptr{new product_store{parent_, id_, "[inserted]", stage::flush}};
   }
 
-  product_store_ptr product_store::make_continuation(std::string_view source,
+  product_store_ptr product_store::make_continuation(std::string source,
                                                      products new_products) const
   {
     return product_store_ptr{
-      new product_store{parent_, id_, source, stage::process, std::move(new_products)}};
+      new product_store{parent_, id_, std::move(source), stage::process, std::move(new_products)}};
   }
 
   product_store_ptr product_store::make_child(std::size_t new_level_number,
                                               std::string const& new_level_name,
-                                              std::string_view source,
+                                              std::string source,
                                               products new_products)
   {
-    return product_store_ptr{new product_store{
-      shared_from_this(), new_level_number, new_level_name, source, std::move(new_products)}};
+    return product_store_ptr{new product_store{shared_from_this(),
+                                               new_level_number,
+                                               new_level_name,
+                                               std::move(source),
+                                               std::move(new_products)}};
   }
 
   product_store_ptr product_store::make_child(std::size_t new_level_number,
                                               std::string const& new_level_name,
-                                              std::string_view source,
+                                              std::string source,
                                               stage processing_stage)
   {
     return product_store_ptr{new product_store{
-      shared_from_this(), new_level_number, new_level_name, source, processing_stage}};
+      shared_from_this(), new_level_number, new_level_name, std::move(source), processing_stage}};
   }
 
   std::string const& product_store::level_name() const noexcept { return id_->level_name(); }
-  std::string_view product_store::source() const noexcept { return source_; }
+  std::string const& product_store::source() const noexcept { return source_; }
   product_store_const_ptr product_store::parent() const noexcept { return parent_; }
   level_id_ptr const& product_store::id() const noexcept { return id_; }
   bool product_store::is_flush() const noexcept { return stage_ == stage::flush; }
diff --git a/phlex/model/product_store.hpp b/phlex/model/product_store.hpp
index 1aed24cc..c0060902 100644
--- a/phlex/model/product_store.hpp
+++ b/phlex/model/product_store.hpp
@@ -17,7 +17,7 @@ namespace phlex::experimental {
   class product_store : public std::enable_shared_from_this<product_store> {
   public:
     ~product_store();
-    static product_store_ptr base();
+    static product_store_ptr base(std::string base_name = "Source");
 
     product_store_const_ptr store_for_product(std::string const& product_name) const;
 
@@ -25,18 +25,18 @@ namespace phlex::experimental {
     auto end() const noexcept { return products_.end(); }
 
     std::string const& level_name() const noexcept;
-    std::string_view source() const noexcept; // FIXME: Think carefully of using std::string_view
+    std::string const& source() const noexcept;
     product_store_const_ptr parent(std::string const& level_name) const noexcept;
     product_store_const_ptr parent() const noexcept;
     product_store_ptr make_flush() const;
-    product_store_ptr make_continuation(std::string_view source, products new_products = {}) const;
+    product_store_ptr make_continuation(std::string source, products new_products = {}) const;
     product_store_ptr make_child(std::size_t new_level_number,
                                  std::string const& new_level_name,
-                                 std::string_view source,
+                                 std::string source,
                                  products new_products);
     product_store_ptr make_child(std::size_t new_level_number,
                                  std::string const& new_level_name,
-                                 std::string_view source = {},
+                                 std::string source = {},
                                  stage st = stage::process);
     level_id_ptr const& id() const noexcept;
     bool is_flush() const noexcept;
@@ -58,26 +58,27 @@ namespace phlex::experimental {
     void add_product(std::string const& key, std::unique_ptr<product<T>>&& t);
 
   private:
-    explicit product_store(product_store_const_ptr parent = nullptr,
-                           level_id_ptr id = level_id::base_ptr(),
-                           std::string_view source = {},
+    explicit product_store(product_store_const_ptr parent,
+                           level_id_ptr id,
+                           std::string source,
                            stage processing_stage = stage::process,
                            products new_products = {});
     explicit product_store(product_store_const_ptr parent,
                            std::size_t new_level_number,
                            std::string const& new_level_name,
-                           std::string_view source,
+                           std::string source,
                            products new_products);
     explicit product_store(product_store_const_ptr parent,
                            std::size_t new_level_number,
                            std::string const& new_level_name,
-                           std::string_view source,
+                           std::string source,
                            stage processing_stage);
 
     product_store_const_ptr parent_{nullptr};
     products products_{};
     level_id_ptr id_;
-    std::string_view source_;
+    std::string
+      source_; // FIXME: Should not have to copy the string (the source should outlive the product store)
     stage stage_;
   };
 
diff --git a/test/hierarchical_nodes.cpp b/test/hierarchical_nodes.cpp
index c72d81e1..588d618b 100644
--- a/test/hierarchical_nodes.cpp
+++ b/test/hierarchical_nodes.cpp
@@ -43,11 +43,11 @@ namespace {
     auto job_store = product_store::base();
     driver.yield(job_store);
     for (unsigned i : std::views::iota(0u, index_limit)) {
-      auto run_store = job_store->make_child(i, "run");
+      auto run_store = job_store->make_child(i, "run", "levels_to_process");
       run_store->add_product<std::time_t>("time", std::time(nullptr));
       driver.yield(run_store);
       for (unsigned j : std::views::iota(0u, number_limit)) {
-        auto event_store = run_store->make_child(j, "event");
+        auto event_store = run_store->make_child(j, "event", "levels_to_process");
         event_store->add_product("number", i + j);
         driver.yield(event_store);
       }