中国科学院数学与系统科学研究院期刊网
POSITIVE SOLUTION OF EVEN ORDER NONLINEAR NEUTRAL DIFFERENCE EQUATIONS WITH VARIABLE DELAY
Feng Jian YANG;Jie Chun LIU
Journal of Systems Science and Mathematical Sciences . 2002, (1): 85 -089 .  DOI: 10.12341/jssms09752