. "Heligoland" . . . "1 July 1890 treaty" . . . . . . . . . "a deal" . "Heligoland\u2013Zanzibar Treaty" . "treaty" . "Heligoland\u2013Zanzibar Treaty (1890)" . . . "Heligoland-Zanzibar Treaty" . . "Anglo-German Agreement" . . "1890 Zanzibar Treaty" . . . "Heligoland\u2013Zanzibar Treaty" . . "the exchange" . "Anglo-German Convention" .