Perhaps you should try some spelling variations:
20 formulae » 2 formulae, 20 formula, 20 formule
10 formulae » 10 formulas, 11 formulae, 17 formulae
2 formulas » _ formulas, 3 formulas, cnf formulas
c receipts » _ receipts, new receipts, all receipts
21 early » 2.1 early, 1 early, 11 early

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: %22medicine %((2 formulas) OR (((20 formulae) OR (10 formulae))))%c receipts%_ prescriptions %21 early works to 1800%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%22medicine %((2 formulas) or (((20 formulae) OR (10 formulae))))%c receipts%_ prescriptions %21 early works to 1800%22".
• Adding a wildcard symbol may retrieve word variants: %22medicine %((2 formulas) or (((20 formulae) OR (10 formulae))))%c receipts%_ prescriptions %21 early works to 1800%22*.