HA (statistics), HB (economic theory), HC (national production), HD10-1341 – Main
HD1375-1395 (real estate) – Business
HD1405-2429 (agriculture and industry) – Main
HD2709-2769 (industry) – Business
HD2771-4730 (industry) – Main
HD9000-9999 (industry) – shared on title by title basis
HE1-328 (transportation & communication) – Main
HE381-5999 (same) – Main
HE6000-9925 (post/telephone/telegraph) – shared
HF1-347 (commerce) – Business
HF347 –499 (same) – Main
HF1001-1650 (same) – Business
HF1701-404 (same) – shared
HF5001-6201 (business) – Business
HG1-188 (finance) – Business
HG210-1486 (money) – Main
HG501-9245 (banking, etc.) – Business.