Saya mau tau Kamus dari Bahasa Duala. Jelaskan dalam bahasa melayu

E. Dinkelacker, Wörterbuch der Duala-Sprache, Hamburg, 1914.

Paul Helmlinger, Dictionnaire duala-français, suivi d'un lexique français-duala. Editions Klincksieck, Paris, 1972.

Johannes Ittmann, edited by E. Kähler-Meyer, Wörterbuch der Duala-Sprache, Dictionnaire de la langue duala, Dictionary of the Duala Language, Dietrich Reimer, Berlin, 1976. The preface evaluates 1 as terse, but good, while 2 has missing and erroneous tone marks.