Perhaps you should try some spelling variations:
nham thuc » nhan thuc, nam thuc, nham thu
cau tren » cu tren, dau tren, ca tren
sach thu » sach thue, sach thieu, sach tham
danh vai » danh sai, danh va, doanh van
hieu van » thien van, lieu va
thu nang » thi nang, thu hang, thu bang
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
vai cau » va cau, van cau, vai cac
tu sach » thu sach, su sach, te sach
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 thu nang x hoi. ((((hieu ve) or (hieu van))) or (hieu va)) nham thuc va danh vai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thu nang x hoi. ((((hieu ve) OR (hieu van))) OR (hieu va)) nham thuc va danh vai cau tren.
• Adding a wildcard symbol may retrieve word variants: tu sach thu nang x hoi. ((((hieu ve) or (hieu van))) or (hieu va)) nham thuc va danh vai cau tren*.