Perhaps you should try some spelling variations:
nam trung » nam trong, tai trung, ba trung
nam truc » nam truoc, nam thuoc, lam truoc
nam thuc » nam thuoc, am thuc, nam thu
dat tren » dat trong, dua tren
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cao hoc » co hoc, cho hoc, chat hoc
hieu ve » hieu va, hieu van
va dan » ca dan, va dao, va dau
ca dat » cai dat, ca dao, ca dan

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 cao hoc. hieu ve ((((nam truc) OR (nam thuc))) or (nam trung)) va dan ca dat tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang cao hoc. hieu ve ((((nam truc) OR (nam thuc))) OR (nam trung)) va dan ca dat tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang cao hoc. hieu ve ((((nam truc) OR (nam thuc))) or (nam trung)) va dan ca dat tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang cao hoc. hieu ve ((((nam truc) OR (nam thuc))) or (nam trung)) va dan ca dat tren*.