Perhaps you should try some spelling variations:
ninh viet » sinh vien, anh viet
dinh viet » danh viet, trinh viet, sinh vien
toc sach » hoc sach, doc sach, thuoc sach
cac duc » cac du, cao duc, cac dac
hieu ve » hieu va, hieu van
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet
ve cac » va cac, vien cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) ty nang ma hoa. hieu ve cac duc va ((dinh viet) or (ninh viet)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ty nang ma hoa. hieu ve cac duc va ((dinh viet) OR (ninh viet)) cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ty nang ma hoa. hieu ve cac duc va ((dinh viet) or (ninh viet)) cua tre*".