Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
cau theo » cau thi, cau tao
toc sac » toc san, hoc sach, doc sach
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
va nam » van nam, ha nam, va nay
va dan » ca dan, va dao, va dau
dan va » doan va, dan ca, ban va
va cau » van cau, va cac, va dau

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sac) or (toc sach)) ky lang xa hoi. hieu va nam thuc va dan va cau theo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sac) OR (toc sach)) ky lang xa hoi. hieu va nam thuc va dan va cau theo.
• Adding a wildcard symbol may retrieve word variants: ((toc sac) or (toc sach)) ky lang xa hoi. hieu va nam thuc va dan va cau theo*.