difficult to classify

References in classic literature ?
Rebecca in particular was so difficult to classify that Miss Dearborn at the end of a fortnight gave up the attempt altogether.
But there are rare cases of AL in which it is very difficult to classify the blasts, as they have morphologic, cytochemical and immunophenotypic characteristics of both myeloid and lymphoid lineages.
Her arguments for what caused the financial crisis are also difficult to classify, as they do not contain much in the way of substantive philosophy or analysis: "Shadow banking is what caused the financial crisis.
Independent processing of smaller surface water bodies, which are difficult to classify in the overall overall classification of the processing.
It may be difficult to classify this attack as terrorism since investigators found no terrorist ties or political motives, but the Virginia court described the killings as "pursuant to the direction or order" of terrorism.
The researchers said a lack of uniform data from death certificates and other records made it difficult to classify deaths as maternal or obstetric.
In addition, the interventions themselves often were described inexactly, or as a matrix of interventions, making them difficult to classify.
Also like Atkinson's novels, Moriarty's work is difficult to classify.
I would find it difficult to classify the risk as a "Machinery Dealer" when the Workers' Comp, classification has a footnote "Operations away from Premises of the Insured to he separately rated.
While digitally streamed content is difficult to classify and tax, at least most consumers understand what is being purchased.
In primary health care, patients often present with physical and mental symptoms, which upon investigation, are difficult to classify in accordance with currently standardized classification system.
The Birth of Theory is an ambitious, original, lucidly written, scrupulously researched, sui generis book that is difficult to classify.