Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
dan vai » dan va, dan tai, dan vat
qua cac » cua cac
sach tu » sach thu, sach ty, sach uu
nang ma » tang ma, sang ma, nang cao
cach tu » cach thuc
qua cao » qua ca, qua cai, qua co
ma hoi » mai hoi, xa hoi, ma hoa
va dan » ca dan, va dao, va dau
vai su » va su, van su, lai su

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 tu) or (cach tu)) nang ma hoi. hieu ((qua cao) OR (qua cac)) duc va dan vai su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach tu) OR (cach tu)) nang ma hoi. hieu ((qua cao) OR (qua cac)) duc va dan vai su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach tu) or (cach tu)) nang ma hoi. hieu ((qua cao) OR (qua cac)) duc va dan vai su triet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach tu) or (cach tu)) nang ma hoi. hieu ((qua cao) OR (qua cac)) duc va dan vai su triet*.