TY - CONF A1 - Wiggenhauser, Herbert T1 - Impact-echo: theory, application and improvements T2 - Advanced Course on Non-Destructive Testing and Evaluation of Concrete Structures, SERC T2 - Advanced Course on Non-Destructive Testing and Evaluation of Concrete Structures, SERC CY - Chennai, India DA - 2006-12-14 PY - 2006 AN - OPUS4-14732 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -