.rf _Am87 .rf _BC89 .rf _Booch86 .rf _Booch91 .rf _Da89 .rf _Eliens89 .rf _El91 .rf _Eliens91 .rf _GC81 .rf _HOB87 .rf _Ho87 .rf _Ka88 .rf _Ko79 .rf _Meyer88 .rf _PCKW89 .rf _PN84 .rf _ST83 .rf _Snyder86 .rf _Su85 .rf _Webster .rf _WZ88 .rf _WWW90