Perhaps you should try some spelling variations:
hieu luan » hieu luat, hieu quan, tieu luan
luan phan » luan van, luan hoan
toc sach » hoc sach, doc sach, thuoc sach
hanh lam » thanh lap, hanh kem, hanh va
hanh lai » hanh tai, thanh lap, thanh loi
cua tre » cua te, cuu tre, cua triet
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
hay va » chay va, day va, may va
xay va » day va, may va, tay va
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ty nang ma hoi. hieu luan phan ((xay va) OR (hay va)) ((hanh lai) or (hanh lam)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty nang ma hoi. hieu luan phan ((xay va) OR (hay va)) ((hanh lai) OR (hanh lam)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty nang ma hoi. hieu luan phan ((xay va) OR (hay va)) ((hanh lai) or (hanh lam)) cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ty nang ma hoi. hieu luan phan ((xay va) OR (hay va)) ((hanh lai) or (hanh lam)) cua tre*.