diff --git a/app/controllers/personal_conferences_controller.rb b/app/controllers/personal_conferences_controller.rb
index bae5aa4..f175f13 100644
--- a/app/controllers/personal_conferences_controller.rb
+++ b/app/controllers/personal_conferences_controller.rb
@@ -40,7 +40,7 @@ class PersonalConferencesController < ApplicationController
       when "period"
           writing_conferences_show = writing_conferences_temp.select {|value| search_all_words(value.duration, params[:keywords])}
       when "publication_date"
-          writing_conferences_show = writing_conferences_temp.select {|value| search_all_words(value.send("publication_date").strftime("%Y/%m/%d").collect{|x| x.title}.join(', '), params[:keywords])}
+          writing_conferences_show = writing_conferences_temp.select {|value| search_all_words(value.send("publication_date").strftime("%Y/%m/%d"), params[:keywords])}
       when "author_type"
           writing_conferences_show = writing_conferences_temp.select {|value| search_all_words(value.conference_author_types.collect{|cat| cat.title}.join(", "), params[:keywords])}
       when "language"