Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
nang mai » nang ma, nang tai, lang mai
tinh dai » trinh dai, tinh da, tinh hai
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cuu tre, cua triet
va tinh » may tinh
tu sach » thu sach, su sach, te sach
mai hoi » mai khoi, dai hoi, lai hoi
ty nang » ky nang, ty xang, ty hang
ve cac » va cac, vien cac
ve cam » ve cham, va cam, ve cai
luc va » duc va, tuc va, loc va

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 nang mai hoi. hieu ((ve cam) OR (ve cac)) luc va tinh dai ((cua tre) or (su triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang mai hoi. hieu ((ve cam) OR (ve cac)) luc va tinh dai ((cua tre) OR (su triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang mai hoi. hieu ((ve cam) OR (ve cac)) luc va tinh dai ((cua tre) or (su triet))".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang mai hoi. hieu ((ve cam) OR (ve cac)) luc va tinh dai ((cua tre) or (su triet))*.