“…Step 4: generalize and categorize codes [11], [16], [24], [30], [38], [40], [41] 2 , [42], [43], [44], [45], [46], [47] , , [48] 4 , [49], [50], [51] 17 Energy [12], [39] 2 Smart cities [2], [10], [27], [52], [53] 5 Manufacturing and industry 4.0 [13], [17]- [19], [54] 5…”