Perhaps you should try some spelling variations:
nam truc » nam truoc, nam thuc, nam trung
hieu van » hieu va, thien van, lieu va
toc sach » hoc sach, doc sach, thuoc sach
hanh vai » hanh vi, hanh tai, hanh van
hanh va » hang va, hanh vi
truc xa » tuc xa, truc va, truoc xay
nang ma » tang ma, sang ma, nang cao
cuu tre » cua tre, cau tren, cau treo
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: ((te sach) or (toc sach)) ky nang ma hoi. hieu van nam truc xa ((hanh vai) OR (hanh va)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky nang ma hoi. hieu van nam truc xa ((hanh vai) OR (hanh va)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (toc sach)) ky nang ma hoi. hieu van nam truc xa ((hanh vai) OR (hanh va)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) ky nang ma hoi. hieu van nam truc xa ((hanh vai) OR (hanh va)) cuu tre*.