TY - JOUR ID - 672 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 - 5 SP - EP - DO - N2 - UR - http://bims.iranjournals.ir/article_672.html L1 - http://bims.iranjournals.ir/article_672_a5897169b8de58a73b14cc1ee2243b18.pdf ER -