effectiveness of personal communication6. August 2020/von feyen https://adconia.de/wp-content/uploads/2018/11/adconiagrey_-1.png 0 0 feyen https://adconia.de/wp-content/uploads/2018/11/adconiagrey_-1.png feyen2020-08-06 15:46:282020-08-06 15:46:50effectiveness of personal communication