Zaenal Akbar Slamet B. I. Ajinagoro G. I. Ohara Iman Firmansyah Bambang Hermanto Laksana Tri Handoko http://arxiv.org/abs/0708.0605 2007 CoRR abs/0708.0605 db/journals/corr/corr0708.html#abs-0708-0605 informal publication