Safety Evaluation of Billboards According to Some Random Factors in the Southwest of Vietnam

BibTeX does not have the right entry for preprints. This is a hack for producing the correct reference:

@Booklet{EasyChair:2519,
  author = {An Hoang Bac},
  title = {Safety Evaluation of Billboards According to Some Random Factors in the Southwest of Vietnam},
  howpublished = {EasyChair Preprint no. 2519},

  year = {EasyChair, 2020}}