Reducing Khat use among Somalis living in Kenya: a controlled pilot study on the modified ASSIST-linked brief intervention delivered in the community oleh Marina Widmann, Bernice Apondi, Abednego Musau, Abdulkadir Hussein Warsame, Maimuna Isse, Victoria Mutiso, Clemens Veltrup, Inga Schalinski, David Ndetei, Michael Odenwald