BibTeX does not have the right entry for preprints. This is a hack for producing the correct reference:
@Booklet{EasyChair:1826,
author = {Larab Moulay and Farid Miloua and Ayad Ahmed Nour El Islam},
title = {Model of Discharge Lamp Sodium With High Pressure},
howpublished = {EasyChair Preprint no. 1826},
year = {EasyChair, 2019}}
