Perhaps you should try some spelling variations:
trinh tai » trinh toan, trinh han, chinh tai
trinh tu » trinh ky, trinh do
tang van » dang van, hoang van, trong van
tu sach » thu sach, su sach, te sach
cam luc » cam xuc, cau luc
cua tre » cua te, cuu tre, cua triet
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
lang ha » long ha
luc va » duc va, tuc va, loc va
va cam » va cham, va cac, va cao

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 ((tang van) or (lang ha)) hoi. hieu va cam luc va ((trinh tai) OR (trinh tu)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((tang van) OR (lang ha)) hoi. hieu va cam luc va ((trinh tai) OR (trinh tu)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((tang van) or (lang ha)) hoi. hieu va cam luc va ((trinh tai) OR (trinh tu)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((tang van) or (lang ha)) hoi. hieu va cam luc va ((trinh tai) OR (trinh tu)) cua tre*.