Perhaps you should try some spelling variations:
thieu sach » chieu sach, thien hach, hieu cach
hoc thieu » toc thieu, hoc hien
trung lan » trong lan, trung can, trung lap
trung van » truong van, trong van, trung va
tung dan » huong dan, trung dai, dung dat
dung dan » dung dat, dung san, huong dan
canh cau » canh chau, can cau, danh cau

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 sach - thanh ((trung lan) or (trung van)) phuong ((tung dan) OR (dung dan)) canh cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thieu sach - thanh ((trung lan) OR (trung van)) phuong ((tung dan) OR (dung dan)) canh cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc thieu sach - thanh ((trung lan) or (trung van)) phuong ((tung dan) OR (dung dan)) canh cau".
• Adding a wildcard symbol may retrieve word variants: hoc thieu sach - thanh ((trung lan) or (trung van)) phuong ((tung dan) OR (dung dan)) canh cau*.