Alex Unya Ambun
Report on quarry site investigation at Sungei Bua Batang Oya GSKL 017/227 Alex Unya Ambun, Gasah Lingkai - 1980 - 1 v.(various pagings) ill. 30 cm
Substantial reserve of good quality sandstone is believed to occur within the ridge
Quarries and quarrying--Batang Oya--Sarawak
Report on quarry site investigation at Sungei Bua Batang Oya GSKL 017/227 Alex Unya Ambun, Gasah Lingkai - 1980 - 1 v.(various pagings) ill. 30 cm
Substantial reserve of good quality sandstone is believed to occur within the ridge
Quarries and quarrying--Batang Oya--Sarawak