“…When R is a (both left and right) Noetherian local ring and M has finite virtual projective dimension, Avramov [4,Theorem 4.4] gave an upper bound for the degree n and showed that the period p is either 1 or 2. On the other hand, using the notion of Tate cohomology, the author [31,Theorem 2.4] obtained a result on the period p without additional assumption on R and M; however, it follows that Tate cohomology gives no information on the degree n. Moreover, there are further results on the values of n and p: for example, [3,Theorem 1.6], [15, the proof of Corollary 6.4], [19,Theorem 1.2] and [30,Proposition 4.3]. We note that eventually periodic modules are examined in the literature such as [9,14,23,16].…”