Laksana khatyaeng (contrast) nai wannakam ruang Phra `Aphaimani khong Sunthon Phu / - Niphon `Insin. (Phak Wicha Phasa Thai, Khana Manutsayasat lae Sangkhommasat, Witthayalai Khru Sakon Nakhon,, 1978)