TY-JUR A2 - Balthazar变量SP - 040475 VL - 2007 AB - SN - 1024-123X UR - HTTPS：//Doi.org/10.1155/2007/40475 Do - 10.1155 / 2007/40475 JF - 工程中的数学问题PB - Hindwai Publishing Corporation KW - ER-