The Satmar group grew rapidly, attracting many new followers. A 1961 survey established that its Williamsburg community included 4,500 people. From the 860 household heads, about 40 percent were neither Satmar nor Sighet Hasidim in the pre-war years. In 1968, Satmar was already New York's largest Hasidic group, with 1,300 households in the city. In addition, there are many Satmar Hasidim in other parts of the United States, and worldwide. As part of his vision of complete isolation from the outside world, Joel encouraged his followers, many of whom were immigrants from former Greater Hungary who spoke primarily German or Hungarian, to use only Yiddish. The sect has its own Yiddish-oriented education system and several publishing houses which provide extensive reading material. Rabbi Yoel Teitelbaum's work in this matter made him, according to Bruce Mitchell, the "most influential figure" in the maintenance of the language in the post-war period. The uniformity of Satmar in America made it easier to teach young people the language, unlike in Europe: George Kranzler noted already in 1961 that the children speak Yiddish much better than their parents.