When The Results Are Too Specific, Go The Other Way

Narrowing is a habit, and like all habits it keeps going after it has stopped helping.

The opposite failure gets much less attention and is just as common. You have narrowed correctly, learned the vocabulary, added the qualifiers, and now you are getting three results, all of them nearly right and none of them what you need. The instinct at this point is to add another term, because adding terms has been working. It will not work now. You have already cut the field down to a handful of documents and further cutting simply removes them one by one until you have nothing and conclude, wrongly, that the answer does not exist.

Recognise the signal: very few results, all of them plausible. That means the material is scarce rather than absent, and scarcity calls for widening. Drop your most specific term, the one you were proudest of. Replace a precise year or place with the general case, on the basis that the answer may be documented for the whole country and not for your suburb, or for the decade and not for the month. Move up one level of category: if the exact product yields nothing, the class of product may be well documented and may answer your question adequately.

Widening also means widening the shape of what you will accept. A question about one narrow case is often answered inside a broader document that never mentions your case by name: a general guidance note, an overview of a whole sector, a set of rules that covers everything of that type. Skilled finders oscillate. They tighten until the results thin out, loosen until they thicken again, and read the pattern of that oscillation as information about how well documented the subject really is.