TY - JOUR ID - 892 TI - Bulletin of the Iranian Mathematical Society JO - Bulletin of the Iranian Mathematical Society JA - BIMS LA - en SN - 1017-060X Y1 - 2016 PY - 2016 VL - 42 IS - 6 SP - EP - DO - N2 - UR - http://bims.iranjournals.ir/article_892.html L1 - http://bims.iranjournals.ir/article_892_76367872db19dee6e35769d297c7cbaf.pdf ER -