The module does not work on the Russian-language sites

Proposed solution (from http://www.drupal.ru/node/76600#comment-486657):

--- /sites/all/modules/similar/views/similar_handler_argument_nid.inc
+++ /sites/all/modules/similar/views/similar_handler_argument_nid.inc
@@ -268,17 +268,20 @@
     // and populate the $text variable with node titles and bodies.
     foreach ($this->value as $nid) {
       $node = node_load($nid);
-      if (isset($node->title) && isset($node->body) && isset($node->body[$node->language])) {
+      if (isset($node->title) && isset($node->body) && (isset($node->body[$node->language]) || isset($node->body['und']))) {
         // Remove punctuation from the title.
-        $title = preg_replace('/[^a-z0-9 _-]+/i', '', $node->title);
+        $title = preg_replace('/[^a-z0-9а-я _-]+/iu', '', $node->title);
 
         // Alter the relevancy of words in the node title if option is selected.
         if ($boolean && !empty($this->options['source_relevance']) && isset($this->options['title_operator'])) {
           $title = $this->alter_node_title($title);
         }
 
         // Strip tags and add slashes only to the body before adding the title.
-        $body = trim(addslashes(strip_tags($node->body[$node->language][0]['value'])));
+        if(isset($node->body[$node->language]))
+          $body = trim(addslashes(strip_tags($node->body[$node->language][0]['value'])));
+        else
+          $body = trim(addslashes(strip_tags($node->body['und'][0]['value'])));
         $text .= " $title $body";
       }
     }