Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
hieu van » hieu va, thien van, lieu va
tan anh » tuan anh, tran anh, toan anh
cao suc » cao duc
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, me hoi
anh vi » hanh vi, anh va, anh ve
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat sach ky nang ((ma hoi) or (ma hoa)). hieu van ((cao suc) OR (cao su)) tan anh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sach ky nang ((ma hoi) OR (ma hoa)). hieu van ((cao suc) OR (cao su)) tan anh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sach ky nang ((ma hoi) or (ma hoa)). hieu van ((cao suc) OR (cao su)) tan anh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: thuat sach ky nang ((ma hoi) or (ma hoa)). hieu van ((cao suc) OR (cao su)) tan anh vi cua tre*.