Columbia subject headings:
Harvard subject headings:
Loggers--Rhine River Valley--History--Congresses.
Lumber trade--Rhine River Valley--History--Congresses.
Timber--Rhine River Valley--Rafting--History--Congresses.
Princeton subject headings:
Loggers--Rhine River Valley--History--Congresses.
Lumber trade--Rhine River Valley--History--Congresses.
Timber--Rhine River Valley--Rafting--History--Congresses.