Perhaps you should try some spelling variations:
nham thuc » nhan thuc, nam thuc, nham thu
hieu van » hieu va, thien van, lieu va
van nham » van nam, van nhan, van tham
tu sach » thu sach, su sach, te sach
co sach » bo sach, cuon sach, hoc sach
thuc va » thuc vat, thuc dan, thuc day
va tinh » may tinh
vai cua » dai cua, hai cua, lai cua
vi cua » di 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: ((tu sach) or (co sach)) ky nang x hoi. hieu van nham thuc va tinh ((vi cua) OR (vai cua)) viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (co sach)) ky nang x hoi. hieu van nham thuc va tinh ((vi cua) OR (vai cua)) viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (co sach)) ky nang x hoi. hieu van nham thuc va tinh ((vi cua) OR (vai cua)) viet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (co sach)) ky nang x hoi. hieu van nham thuc va tinh ((vi cua) OR (vai cua)) viet*.