Perhaps you should try some spelling variations:
thieu tach » thien hach, chieu sach, hieu cach
chiet tach » chieu sach
thanh tung » thanh cong
nang cong » nang song, dang cong, bang cong
tung cam » dung cam, trung cap, tung pham
tan thai » ban thai, tan tai, van thai
tay thai » lay thai, toc thai, y thai

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((thieu tach) or (chiet tach)) - thanh tung cam nang cong ((tan thai) OR (tay thai)) cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu tach) OR (chiet tach)) - thanh tung cam nang cong ((tan thai) OR (tay thai)) cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu tach) or (chiet tach)) - thanh tung cam nang cong ((tan thai) OR (tay thai)) cao".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu tach) or (chiet tach)) - thanh tung cam nang cong ((tan thai) OR (tay thai)) cao*.