Danish Sign Language
Henri Wittmann (1991)[2] assigned DSL to the French Sign Language family because of similarities in vocabulary.Peter Atke Castberg studied deaf education in Europe for two years (1803–1805), including at l'Épée's school in Paris, and founded the first deaf school in Denmark in 1807, where Danish Sign Language (DTS) developed.[3] In 1977, the Danish Deaf Association adopted 'the international manual alphabet', which was an almost exact copy of the American manual alphabet, with minor differences and additional signs for the æ, ø and å.[3] Norwegian Sign Language is generally thought to be a descendant of DSL.[3] Icelandic Sign Language is closer; 37% of a set of analyzed signs (Aldersson 2006) were completely different in structure and a further 16% were similar but not the same.