The decipherment and classification of Hieroglyphic Luwian was much more difficult. In the 1920s, there were a number of failed attempts. In the 1930s some individual logograms and syllabic signs were correctly identified. At this point the classification of the language was not yet clear and, since it was believed to be a form of Hittite, it was referred to as "Hieroglyphic Hittite". After a break in research due to the Second World War, there was breakthrough in 1947 with the discovery and publication of a Phoenician-Hieroglyphic Luwian bilingual text by Helmuth Theodor Bossert. The reading of several syllabic signs was still faulty, however, and as a result it was not realised that the cuneiform and hieroglyphic texts recorded the same language.