Perhaps you should try some spelling variations:
sach thi » sach tai, sach thieu, sach tham
sach thu » sach thue, sach thieu, sach tham
nang cau » nang cao, hang cau, nang dau
tu triet » su triet, tu thiet, tu trien
qua cam » qua cham, qua cac, qua ca
cam tuc » cam xuc, cam tu, nam thuc
tuc van » thuc van, truc van, tuc va
han tai » hang tai, nhan tai, toan tai
van tai » von tai, van tuan

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 thi) or (sach thu)) nang cau hoi. hieu qua cam tuc van ((han tai) OR (van tai)) tu triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach thi) OR (sach thu)) nang cau hoi. hieu qua cam tuc van ((han tai) OR (van tai)) tu triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach thi) or (sach thu)) nang cau hoi. hieu qua cam tuc van ((han tai) OR (van tai)) tu triet*".