31=17,4; 32=17,5; 32a=17,6; 34=18,4; 35=19,1; 43=23,3; 44=23,4; 60=30,2; 68=33,4; 72=34,4; 79=36,6; 83=38,1; 87=39,2; 89=40,1; 91=41,2; 94=42,3; 96=43: Engineering bulletin (ISSN: 0097-0344)
60=2; 68=4; 72=5; 76=6; 79=7; 83=8; 87=9; 89=10; 91=11; 94=12; 96=13 von: Industrial Waste Conference: Proceedings of the ... Industrial Waste Conference (ISSN: 0073-7682)
35=21; 44=25 von: Road School: Proceedings of the Annual Road School
43=3 von: Personnel bulletin