The preferred term to use in your sentence is further. The usage panel for The American Heritage Dictionary prefers that farther be restricted to sentences in which it refers to literal distance.
In the opening paragraph of his paper, Fred Miller contends that "the question whether Rand's ethics is 'Aristotelian' should not turn merely on whether Rand and Aristotle make similar moral pronouncements, but on whether there are deeper parallels involving fundamental principles and methodology." [Concerning judgements of intellectual similarity, see further, the exchange between Peikoff (Prof. E), Gotthelf (Prof. B), and Rand in IOE app. 221-22.] At that point, Miller enters a note concerning Jack Wheeler's 1984 essay, saying: "Although Wheeler makes some interesting comparisons, he tends to exaggerate the parallels between Rand and Aristotle and makes no attempt to explain why Rand was critical of Aristotle's method in ethics. Nor does he mention 'Causality Versus Duty'."
As you know, in her essay "Causality Versus Duty" (1974), Rand addressed a number of important issues in moral philosophy. One of them was the choice open to human beings concerning their ultimate ends. Professor Miller's paper included that issue prominently in his comparison and appraisal of the ethics of Rand and Aristotle.