Could you please explain and total how they got the 67

TABLE 1 Period Wise List of Challenges

TABLE 1 Period Wise List of Challenges Name of Database Google Scholar IEEE SpringerLink ACM ScienceDirect Total After selecting 23 Technique (Total) Search Result Primary Selection 13900 55 2074 398 4795 21222 papers in Snow 81 02 33 22 31 169 Bowling Final Selection 37 00 03 00 04 44 67