Perhaps you should try some spelling variations:
hac thuc » ha thuc, thach thuc, thuc thuc
thanh va » thanh van, hanh va, thanh ha
va thanh » gia thanh, ban thanh, va tinh
hoc thuc » hoc huu
hieu van » hieu va, thien van, lieu va
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky
va cua » va chua, via cua, ca cua
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu ((sach ty) or (sac ky)) nang x hoi. hieu van ((hac thuc) OR (hoc thuc)) va thanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu ((sach ty) OR (sac ky)) nang x hoi. hieu van ((hac thuc) OR (hoc thuc)) va thanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu ((sach ty) or (sac ky)) nang x hoi. hieu van ((hac thuc) OR (hoc thuc)) va thanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: vu ((sach ty) or (sac ky)) nang x hoi. hieu van ((hac thuc) OR (hoc thuc)) va thanh va cua tre*.