Perhaps you should try some spelling variations:
trinh vat » trinh van, trinh luat, sinh vat
hang cong » dang cong, hang nong, bang cong
khoan cam » khoa cam, khoan va, phan cam
trinh va » trinh van, trinh ve, trinh vi
cong dan » cong san, cong tan, huong dan
khan cap » khan ap, than cap, phan cac
ha tinh » va tinh, may tinh
ho ha » pho ha, ho hap, o ha

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: ho ha tinh - hanh ((trinh va) OR (trinh vat)) hang cong dan ((khan cap) OR (khoan cam))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho ha tinh - hanh ((trinh va) OR (trinh vat)) hang cong dan ((khan cap) or (khoan cam))~".
• Adding a wildcard symbol may retrieve word variants: ho ha tinh - hanh ((trinh va) OR (trinh vat)) hang cong dan ((khan cap) or (khoan cam))*.