The phrase "already explained in the" is correct and usable in written English.
You can use it when referring to information or details that have been previously clarified or described in a document or conversation.
Example: "The procedure for submitting your application is already explained in the guidelines provided earlier."
Alternatives: "previously detailed in the" or "already outlined in the".
Please don't ask basic questions about general use of the calculator (how to graph functions or delete variables, etc). that are already explained in the calculator's manual.
All these modules (except security module) are already explained in the earlier sections.
The detail theory of the method is already explained in the previous sections.
The genetic disorder linked to this region is OMIM #426000 and it could play a part in Y-linked spermatogenic failure as already explained in the AZF gene section.
This is in line with the theoretical expectation that the training of the QSAR model and the calculation of the AD are two different tasks, as already explained in the "Methods" section.
These issues are already explained in the book and in the technical appendix, but they probably need to be clarified.
The values of (gamma_{S}^{LW}) and (I_{SL}^{AB}) (see "Methods") can be derived from contact angle measurements, using several liquids with varying LW and polar components as already explained in this paper.
He had already explained, in "Forced Entries: The Downtown Diaries 1971-1973" (1987), the second published volume of his journals, that "poetry can unleash a terrible fear.
We can conclude that the typical problem connected to interference management, as already explained in Section 2., lies in the unpredictability of the deployed scenario.
I've already explained in an earlier post the major features of the new constitutional order.
The judge noted that one of 10 questions the jury sent him on Tuesday, after three days of deliberations, sought an explanation of the requirement to prove a defendant's guilt "beyond a reasonable doubt" — an issue the judge said he had already explained in writing, saying that the wording was in plain English and its meaning self-evident.
