public async Task <RetrievedBookInfoDto> FindBookByIsbnAsync(string isbn, int organizationId) { var bookAlreadyExists = _booksDbSet .Any(book => book.OrganizationId == organizationId && book.Code == isbn); _bookServiceValidator.CheckIfBookAlreadyExists(bookAlreadyExists); var result = await _bookInfoService.FindBookByIsbnAsync(isbn); _bookServiceValidator.CheckIfBookWasFoundByIsbnFromExternalProvider(result); var retrievedBookDto = MapBookInfoToDto(result); return(retrievedBookDto); }