diff --git a/src/file/csv/AbstractReader.php b/src/file/csv/AbstractReader.php
index e5b2a15..6a8444e 100644
--- a/src/file/csv/AbstractReader.php
+++ b/src/file/csv/AbstractReader.php
@@ -2,6 +2,9 @@
 namespace nur\sery\file\csv;
 
 use IteratorAggregate;
+use nur\sery\php\func;
+use nur\sery\php\time\Date;
+use nur\sery\php\time\DateTime;
 
 abstract class AbstractReader  implements IReader {
   const SCHEMA = null;
@@ -42,4 +45,13 @@ abstract class AbstractReader  implements IReader {
     $row = array_combine($this->headers, $row);
     return true;
   }
+
+  protected function verifixCol(&$col): void {
+    # conversion Date et DateTime
+    if (DateTime::isa_datetime($col, true)) {
+      $col = new DateTime($col);
+    } elseif (DateTime::isa_date($col, true)) {
+      $col = new Date($col);
+    }
+  }
 }
diff --git a/src/file/csv/CsvReader.php b/src/file/csv/CsvReader.php
index f83c507..5ea0c8b 100644
--- a/src/file/csv/CsvReader.php
+++ b/src/file/csv/CsvReader.php
@@ -2,22 +2,14 @@
 namespace nur\sery\file\csv;
 
 use nur\sery\file\FileReader;
-use nur\sery\php\time\Date;
-use nur\sery\php\time\DateTime;
 
 class CsvReader extends AbstractReader {
   function getIterator() {
     $reader = new FileReader($this->input);
     while (($row = $reader->fgetcsv()) !== null) {
       foreach ($row as &$col) {
-        # conversion Date et DateTime
-        if (DateTime::isa_datetime($col, true)) {
-          $col = new DateTime($col);
-        } elseif (DateTime::isa_date($col, true)) {
-          $col = new Date($col);
-        }
+        $this->verifixCol($col);
       }; unset($col);
-
       if ($this->cook($row)) {
         yield $row;
         $this->idest++;
diff --git a/src/file/csv/SsReader.php b/src/file/csv/SsReader.php
index 3ce06e6..151b971 100644
--- a/src/file/csv/SsReader.php
+++ b/src/file/csv/SsReader.php
@@ -77,9 +77,9 @@ class SsReader extends AbstractReader {
       for ($ncol = 1; $ncol <= $nbCols; $ncol++) {
         if ($ws->cellExistsByColumnAndRow($ncol, $nrow)) {
           $cell = $ws->getCellByColumnAndRow($ncol, $nrow);
-          $value = $cell->getValue();
-          if ($value instanceof RichText) {
-            $value = $value->getPlainText();
+          $col = $cell->getValue();
+          if ($col instanceof RichText) {
+            $col = $col->getPlainText();
           } else {
             $dataType = $cell->getDataType();
             if ($dataType == DataType::TYPE_NUMERIC || $dataType == DataType::TYPE_FORMULA) {
@@ -101,18 +101,13 @@ class SsReader extends AbstractReader {
                 }
               }
             }
-            $value = $cell->getFormattedValue();
-            # conversion Date et DateTime
-            if (DateTime::isa_datetime($value, true)) {
-              $value = new DateTime($value);
-            } elseif (DateTime::isa_date($value, true)) {
-              $value = new Date($value);
-            }
+            $col = $cell->getFormattedValue();
+            $this->verifixCol($col);
           }
         } else {
-          $value = null;
+          $col = null;
         }
-        $row[] = $value;
+        $row[] = $col;
       }
       if ($this->cook($row)) {
         yield $row;
diff --git a/src/php/time/DateTime.php b/src/php/time/DateTime.php
index 589f1dd..24310b8 100644
--- a/src/php/time/DateTime.php
+++ b/src/php/time/DateTime.php
@@ -35,6 +35,7 @@ class DateTime extends \DateTime {
   const YMDHISZ_PATTERN = '/^((?:\d{2})?\d{2})(\d{2})(\d{2})[tT](\d{2})(\d{2})(\d{2})?([zZ])?$/';
 
   static function isa($datetime): bool {
+    if ($datetime === null) return false;
     if ($datetime instanceof DateTimeInterface) return true;
     if (!is_int($datetime) && !is_string($datetime)) return false;
     return preg_match(self::DMY_PATTERN, $datetime) ||
@@ -44,17 +45,19 @@ class DateTime extends \DateTime {
   }
 
   static function isa_datetime($datetime, bool $frOnly=false): bool {
+    if ($datetime === null) return false;
     if ($datetime instanceof DateTimeInterface) return true;
     if (!is_int($datetime) && !is_string($datetime)) return false;
     return preg_match(self::DMYHIS_PATTERN, $datetime) ||
       (!$frOnly && preg_match(self::YMDHISZ_PATTERN, $datetime));
   }
 
-  static function isa_date($datetime, bool $frOnly=false): bool {
-    if ($datetime instanceof DateTimeInterface) return true;
-    if (!is_int($datetime) && !is_string($datetime)) return false;
-    return preg_match(self::DMY_PATTERN, $datetime) ||
-      (!$frOnly && preg_match(self::YMD_PATTERN, $datetime));
+  static function isa_date($date, bool $frOnly=false): bool {
+    if ($date === null) return false;
+    if ($date instanceof DateTimeInterface) return true;
+    if (!is_int($date) && !is_string($date)) return false;
+    return preg_match(self::DMY_PATTERN, $date) ||
+      (!$frOnly && preg_match(self::YMD_PATTERN, $date));
   }
 
   static function _YmdHMSZ_format(\DateTime $datetime): string {