The phrase "ascertained by reference" is correct and usable in written English.
It can be used in contexts where you need to indicate that something has been determined or verified by consulting a source or document.
Example: "The final decision was ascertained by reference to the company's policy manual."
Alternatives: "determined by consulting" or "verified through reference".
In both cases the Supreme Court instructed that product and market definitions were to be ascertained by reference to evidence of consumers' perception of the nature of the products and the markets for them, rather than to abstract or metaphysical assumptions as to the configuration of the "product" and the "market".
We presume it would not be doubted that if the complainants had been taxed on capital invested in the business, such taxation would not have been obnoxious to constitutional objection, but because they had no capital invested the tax was ascertained by reference to the amount of their commissions, which, when received, were no less their property than their capital would have been.
Those who are able but unwilling to work "must somehow support themselves" (JF 179; cf. PL 182n).. Disability payments to meet the needs of severely handicapped citizens who are permanently unable to work are not ascertained by reference to the difference principle for Rawls, but instead are to be determined by principles of assistance, which he leaves unspecified (PL 272n).
The present study was designed to ascertain, by reference to odds ratio estimates of relative risk by tumor size and histologic grade, whether this was more likely to be due to increased innate predisposition of dense parenchymal patterns to grade 3 tumors, or to dedifferentiation of cases missed at screening due to dense patterns.
Analytical accuracy was ascertained by analyzing commercially available urine reference materials (Concha et al. 2010).
It is possible that Aboriginality as reported in the notification data or any of the linked databases may be inaccurate, and reported Aboriginality is likely to be ascertained by various methods, including through reference to previous medical records, or as an individual judgement based on a person's appearance.
The parental origin of each chromosome, or the chromosome segment in recombinant chromosomes, in the embryo cell is then ascertained by comparison with the genotype of the reference.
In addition, the phylogenetic performance of some of these SCPCH was ascertained by sequencing additional taxa and comparing phylogenies with ITS reference trees.
The Tn 4401 sequence present in each clinical isolate was ascertained by BLASTn comparisons of de novo assemblies with the reference Tn 4401b isoform (GenBank accession no. EU176013.1).
Time to healing of the reference ulcer was recorded by nurses and independently ascertained by blinded investigators using digital photographs.
The quality of the ligands in the final samples was ascertained by comparison of one-dimensional proton spectra of the samples to reference ligand spectra.
