Perhaps you should try some spelling variations:
8.4 modern » 14 modern, 8.4 model, 24 modern
8.4 models » 2.4 models, 1.4 models, 4.4 models
5.4 models » 2.4 models, 14 models
2.4 model » 2.4 models, 6.4 model, 1.4 model
24 model » 14 model, o4 model, 6.4 model

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: %22history%((((24 model) OR (2.4 model))) OR (((((8.4 modern) OR (((8.4 models) OR (3.4 model))))) OR (5.4 models))))%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%22history%((((24 model) OR (2.4 model))) or (((((8.4 modern) or (((8.4 models) or (3.4 model))))) or (5.4 models))))%22".
• Adding a wildcard symbol may retrieve word variants: %22history%((((24 model) OR (2.4 model))) or (((((8.4 modern) or (((8.4 models) or (3.4 model))))) or (5.4 models))))%22*.