Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
danh ve » dinh ve, hanh ve, anh ve
cu tren » tu tren, dua tren
x hoi » o hoi, x ho
5 hoi » o hoi
ve cu » ve cau, ve chu, ve cua

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 ky nang ((((x hoi) OR (5 hoi))) or (xa hoi)). hieu van nam thuc va danh ve cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((((x hoi) OR (5 hoi))) OR (xa hoi)). hieu van nam thuc va danh ve cu tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((((x hoi) OR (5 hoi))) or (xa hoi)). hieu van nam thuc va danh ve cu tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((((x hoi) OR (5 hoi))) or (xa hoi)). hieu van nam thuc va danh ve cu tren*.