The phrase "as the first source" is correct and usable in written English.
It can be used when referring to the initial or primary origin of information or data in a discussion or analysis.
Example: "In our research, we will reference the study conducted by Smith et al. as the first source of our findings."
Alternatives: "as the primary source" or "as the initial source".
In his suit, the film-maker claimed Gawker "crossed the journalistic line by promoting itself to the public as the first source to read the entire screenplay illegally".
The voltaic cell, though important as the first source of continuous electricity, is of limited use because it begins losing power rapidly as current is drawn.
The researchers said their study "represents the first attempt to address the problem of the origin of syphilis using molecular genetics, as well as the first source of information regarding the genetic makeup of nonvenereal strains from the Western Hemisphere".
Rather than merely publishing a news story reporting that Plaintiff's screenplay may have been circulating in Hollywood without his permission, Gawker Media crossed the journalistic line by promoting itself to the public as the first source to read the entire Screenplay illegally".
But when Veronica Hurst, the O.E.D.'s chief bibliographer recently encountered the slip for "revirginize" and saw "The Meanderings of Memory" quoted as the first source for the word's appearance in 1852 ("Where that cosmetic…Shall e'er revirginize that brow's abuse," the listing says), she tried to locate the book.
Equation (7) means that, in a T-segment, if the total energy of the TF units labeled as the first source is stronger than that of the TF units labeled as the second source, all the TF units in the T-segment are labeled as the first source; otherwise, they are labeled as the second source.
In this context, Will is identified as "origo prima" (the first source), though it is only directly described as the "source" of form.
The most important factor in the development of calves is the appropriate and immediate consumption of colostrum post-partum, as it is the first source of nutrients after birth [ 2].
Facing circulating miRNAs as cancer biomarker molecules, the first source of variability to be considered is related to the tumor itself.
The companies first established the cross-licensing agreement that gives them access to each other's technologies in 1976, when AMD signed on to serve as the second source for the 8086 chip, the microprocessor used in International Business Machines' personal computers.
Interestingly, however this was only recorded as the third source actually used.
