diff --git a/dev.metalisp.survey.asd b/dev.metalisp.survey.asd
index 8bb5ec5..5351cdc 100644
--- a/dev.metalisp.survey.asd
+++ b/dev.metalisp.survey.asd
@@ -2,7 +2,7 @@
 
 (defsystem "dev.metalisp.survey"
   :description "Create questionnaires and analyze the results."
-  :version "0.5.41"
+  :version "0.5.42"
   :author "Marcus Kammer <marcus.kammer@mailbox.org>"
   :source-control (:git "https://code.metalisp.dev/marcuskammer/dev.metalisp.survey.git")
   :licence "MIT"
diff --git a/src/models/survey.lisp b/src/models/survey.lisp
index 1658236..1be330c 100644
--- a/src/models/survey.lisp
+++ b/src/models/survey.lisp
@@ -31,34 +31,24 @@
               (uiop:merge-pathnames* uid-str
                                      (ml-survey/fileops:ensure-surveys-dir)))))))
 
-(defgeneric survey-id-p (survey)
-  (:documentation "Check if the survey ID is present in the surveys database."))
-
-(defgeneric survey-data-dir-files (survey)
-  (:documentation "Get the list of files in the survey's data directory."))
-
-(defgeneric survey-data-dir-p (survey)
-  (:documentation "Check if the survey's data directory exists."))
-
-(defgeneric survey-properties-title (survey)
-  (:documentation "Get title property."))
-
-(defgeneric survey-properties-description (survey)
-  (:documentation "Get description property."))
-
 (defmethod survey-uid-p ((survey survey))
+  "Check if the survey ID is present in the surveys database."
   (filter-surveys-by-uid (survey-uid survey)))
 
 (defmethod survey-data-dir-files ((survey survey))
+  "Get the list of files in the survey's data directory."
   (uiop:directory-files (survey-data-dir survey)))
 
 (defmethod survey-data-dir-p ((survey survey))
+  "Check if the survey's data directory exists."
   (uiop:directory-exists-p (survey-data-dir survey)))
 
 (defmethod survey-properties-title ((survey survey))
+  "Get title property."
   (cdr (assoc "title" (survey-properties survey) :test #'string-equal)))
 
 (defmethod survey-properties-description ((survey survey))
+  "Get description property."
   (cdr (assoc "description" (survey-properties survey) :test #'string-equal)))
 
 (defmethod survey-questionnaires ((survey survey) &optional make-fn)