Yinshui Xia Xunwei Wu Penjung Wang Design of Ternary Schmitt Triggers Based on Its Sequential Characteristics. 156-160 2002 conf/ismvl/2002 ISMVL http://computer.org/proceedings/ismvl/1462/14620156abs.htm db/conf/ismvl/ismvl2002.html#XiaWW02