1996  Ishibashi, Fujikawa & Nakornsri, p.178: Locality 1:Reddish shale containing ammonoids etc., reddish massive
               hard siliceous shale  block of 2 m thickness.
     2004  Zhou & Liengjarern: 318, fig.1, BNP, 10 km south of WRC; Map 5343 IV, Grid 87660-2690.