Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
nang cau » nang cao, hang cau, nang dau
cau tren » cu tren, dau tren, ca tren
sach ty » sach y, sach tu, xach tay
hieu va » lieu va, hieu qua
cao tuc » dao tuc, cao duc, cao suc
va cao » va cac, va co, va dao
tuc ca » tuc cac, tuc cua, tuc xa
ca dan » cac dan, ca dao
ca cau » cua cau, cac cau, can cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach ty) OR (sach thu)) nang cau hoi. hieu va cao tuc ca dan ca cau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) OR (sach thu)) nang cau hoi. hieu va cao tuc ca dan ca cau tren".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) OR (sach thu)) nang cau hoi. hieu va cao tuc ca dan ca cau tren*.