Aldila, D.; Azizah, N.; Handari, B.D. 2020. Optimal control problem arises from illegal poaching of southern white rhino mathematical model. Advances in Difference Equations 2020, 605. doi.org/10.1186/s13662-020-03062-5 { copied = true; setTimeout(() => copied = false, 10000); }).catch(err => { console.error('Failed to copy:', err); }); " type="button" :class="copied ? 'bg-secondary border-secondary' : 'border-primary hover:bg-primary'" class="group lg:min-w-64 flex items-center justify-between gap-5 border border-solid px-5 py-2 cursor-pointer transition-colors"> PDF download available