diff --git a/app/models/book.rb b/app/models/book.rb
index 03b559c..63ea980 100644
--- a/app/models/book.rb
+++ b/app/models/book.rb
@@ -152,9 +152,9 @@ class Book
   def get_plugin_field_data(field)
     case field
     when "book_paper_type"
-      value = self.book_type.title rescue ""
+      value = (self.book_type.title rescue "")
     when "author_type"
-      value = self.book_author_types.collect{|type| type.title}.join(',') rescue ""
+      value = (self.book_author_types.collect{|type| type.title}.join(',') rescue "")
     when "author_name"
       value = []
       ([I18n.locale]+(Site.first.in_use_locales-[I18n.locale])).each do |locale|
@@ -180,7 +180,7 @@ class Book
     when "authors"
       value = get_authors_show(self)
     else
-      value = self.send(field) rescue ""
+      value = (self.send(field) rescue "")
     end
 
     value = (value =~ /\A#{URI::regexp(['http', 'https'])}\z/) ? "<a href='#{value}' target='blank'>#{value}</a>" : value