diff --git a/src/ext/spreadsheet/SpoutBuilder.php b/src/ext/spreadsheet/SpoutBuilder.php
index ad0d72b..113d7dc 100644
--- a/src/ext/spreadsheet/SpoutBuilder.php
+++ b/src/ext/spreadsheet/SpoutBuilder.php
@@ -89,6 +89,7 @@ class SpoutBuilder extends AbstractBuilder {
       $this->wroteHeaders = false;
       $this->built = false;
     }
+    $wsname ??= $params["wsname"] ?? null;
     if ($wsname !== null) $ws->setName($wsname);
     $sheetView = (new SheetView())
       ->setFreezeRow(2);
diff --git a/src/ext/spreadsheet/SpoutReader.php b/src/ext/spreadsheet/SpoutReader.php
index 6e5551a..3df5131 100644
--- a/src/ext/spreadsheet/SpoutReader.php
+++ b/src/ext/spreadsheet/SpoutReader.php
@@ -11,18 +11,41 @@ class SpoutReader extends AbstractReader {
   function __construct($input, ?array $params=null) {
     parent::__construct($input, $params);
     $this->ssType = $params["ss_type"] ?? null;
-    $this->wsname = $params["wsname"] ?? static::WSNAME;
+    $this->allSheets = $params["all_sheets"] ?? true;
+    $wsname = static::WSNAME;
+    if ($params !== null && array_key_exists("wsname", $params)) {
+      # spécifié par l'utilisateur: $allSheets = false
+      $this->setWsname($params["wsname"]);
+    } elseif ($wsname !== null) {
+      # valeur non nulle de la classe: $allSheets = false
+      $this->setWsname($wsname);
+    } else {
+      # pas de valeur définie dans la classe, laisser $allSheets à sa valeur
+      # actuelle
+      $this->wsname = null;
+    }
   }
 
   protected ?string $ssType;
 
+  /** @var bool faut-il retourner les lignes de toutes les feuilles? */
+  protected bool $allSheets;
+
+  function setAllSheets(bool $allSheets=true): self {
+    $this->allSheets = $allSheets;
+    return $this;
+  }
+
   protected $wsname;
 
   /**
    * @param string|int|null $wsname
+   *
+   * NB: appeler cette méthode réinitialise $allSheets à false
    */
   function setWsname($wsname): self {
     $this->wsname = $wsname;
+    $this->allSheets = true;
     return $this;
   }
 
@@ -40,27 +63,35 @@ class SpoutReader extends AbstractReader {
     }
     $ss->open($this->input);
     try {
-      $found = false;
+      $allSheets = $this->allSheets;
+      $wsname = $this->wsname;
+      $first = true;
       foreach ($ss->getSheetIterator() as $ws) {
-        if ($this->wsname === null || $this->wsname === $ws->getName()) {
-          $found = true;
-          break;
+        if ($allSheets) $found = true;
+        else $found = $wsname === null || $wsname === $ws->getName();
+        if ($found) {
+          if ($first) {
+            $first = false;
+          } else {
+            yield null;
+            # on garde le même schéma le cas échéant, mais supprimer headers
+            # pour permettre son recalcul
+            $this->headers = null;
+          }
+          $this->isrc = $this->idest = 0;
+          foreach ($ws->getRowIterator() as $row) {
+            $row = $row->toArray();
+            foreach ($row as &$col) {
+              $this->verifixCol($col);
+            }; unset($col);
+            if ($this->cook($row)) {
+              yield $row;
+              $this->idest++;
+            }
+            $this->isrc++;
+          }
         }
       }
-      if (!$found) return;
-
-      $this->isrc = $this->idest = 0;
-      foreach ($ws->getRowIterator() as $row) {
-        $row = $row->toArray();
-        foreach ($row as &$col) {
-          $this->verifixCol($col);
-        }; unset($col);
-        if ($this->cook($row)) {
-          yield $row;
-          $this->idest++;
-        }
-        $this->isrc++;
-      }
     } finally {
       $ss->close();
     }