Perhaps you should try some spelling variations:
thien van » thi van
dinh tai » dinh toai, dinh tri, dinh thi
danh tai » doanh tai, hanh tai, anh tai
cua viet » ca viet, hoa viet, cua vat
thu sach » tu sach, thuat sach, thuoc sach
ty nang » ky nang, ty xang, ty hang
van cac » van hac, van cau, van bac
cac dai » cac dan, cac bai, can dai
su sach » so sach, vu sach
nang o » nang co, nang ho, nang ro
dai va » mai va
o hai » co hai, so hai, o lai

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) or (thu sach)) ty nang o hai. thien van cac dai va ((danh tai) OR (dinh tai)) cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (thu sach)) ty nang o hai. thien van cac dai va ((danh tai) OR (dinh tai)) cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (thu sach)) ty nang o hai. thien van cac dai va ((danh tai) OR (dinh tai)) cua viet".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (thu sach)) ty nang o hai. thien van cac dai va ((danh tai) OR (dinh tai)) cua viet*.