Classification
628 - Sanitary & municipal engineering
7
665 - Industrial oils, fats, waxes & gases
7
541 - Physical chemistry
6
547 - Organic chemistry
5
661 - Industrial chemicals
4
660 - Chemical engineering
3
363 - Other social problems & services
2
540 - Chemistry & allied sciences
2
621 - Applied physics
2
668 - Technology of other organic products
2
551 - Geology, hydrology & meteorology
1
553 - Economic geology
1
574 - [Unassigned]
1
622 - Mining & related operations
1
662 - Explosives, fuels & related products
1