Perhaps you should try some spelling variations:
nham thuc » nhan thuc, nham thu, pham thuc
toc sach » doc sach, thuoc sach, nuoc sach
hieu van » hieu va, thien van, lieu va
danh sai » dung sai, danh bat, danh dau
nam thuc » nam thuoc, am thuc, nam thu
hoc sach » hoc sinh, hoc cac, hoc anh
nang xa » nang x, lang xa, nang ma
va danh » va dinh, va dan, va hanh
sai cua » dai cua, hai cua, lai cua
cua tre » cua te, cuu tre, cua triet

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) or (hoc sach)) ky nang xa hoi. hieu van ((nham thuc) OR (nam thuc)) va danh sai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) ky nang xa hoi. hieu van ((nham thuc) OR (nam thuc)) va danh sai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (hoc sach)) ky nang xa hoi. hieu van ((nham thuc) OR (nam thuc)) va danh sai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (hoc sach)) ky nang xa hoi. hieu van ((nham thuc) OR (nam thuc)) va danh sai cua tre*.