TY - JOUR ID - 651 TI - Bulletin of the Iranian Mathematical Society JO - Bulletin of the Iranian Mathematical Society JA - BIMS LA - en SN - 1017-060X Y1 - 2015 PY - 2015 VL - 41 IS - 4 SP - EP - DO - N2 - UR - http://bims.iranjournals.ir/article_651.html L1 - http://bims.iranjournals.ir/article_651_7df15320a77ce91682cbf112c0f46d88.pdf ER -