diff --git a/app/controllers/personal_books_controller.rb b/app/controllers/personal_books_controller.rb
index 608ac4a..7a7abb9 100644
--- a/app/controllers/personal_books_controller.rb
+++ b/app/controllers/personal_books_controller.rb
@@ -30,7 +30,7 @@ class PersonalBooksController < ApplicationController
       case params[:selectbox]
       when "book_title", "extracted_chapters", "default"
         if params[:selectbox] == "dafault"
-          search_temp = "book_title"
+          search_temp = 'book_title'
         else
           search_temp = params[:selectbox]
           trans = params[:selectbox]