Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
hoa hoi » khoa hoi, hoa hoc, hoa doi
ky dang » ky nang, ky danh
hieu le » hieu ve, hieu he, hieu ly
le nam » ly nam, he nam, le na
ha hoi » ha noi, xa hoi, va hoi
vai va » mai va, dai va, hai va
vi va » vi van, vu va, bi va

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 dang ((ha hoi) or (hoa hoi)). hieu le nam thuc va hanh ((vi va) OR (vai va)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky dang ((ha hoi) OR (hoa hoi)). hieu le nam thuc va hanh ((vi va) OR (vai va)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky dang ((ha hoi) or (hoa hoi)). hieu le nam thuc va hanh ((vi va) OR (vai va)) triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky dang ((ha hoi) or (hoa hoi)). hieu le nam thuc va hanh ((vi va) OR (vai va)) triet*.