Perhaps you should try some spelling variations:
khong trong » khoang trong, thong trong, phong trong
hieu quang » thieu quang, hieu quan, hieu qua
trung tuan » trung thanh, tran tuan, truong thanh
hieu lang » chieu sang, nhieu tang, hieu van
trong dan » trong dang, trong san, trong tan
dan phan » doan phan, dan chan, van phan
phan cau » phan dau, phan cac, phan tu

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: doi ((hieu lang) OR (hieu quang)) - thanh ((trung tuan) OR (trung tam)) khong trong dan phan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doi ((hieu lang) or (hieu quang)) - thanh ((trung tuan) OR (trung tam)) khong trong dan phan cau~".
• Adding a wildcard symbol may retrieve word variants: doi ((hieu lang) or (hieu quang)) - thanh ((trung tuan) OR (trung tam)) khong trong dan phan cau*.