Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
thuc dan » thuc hanh, hoc dan, thuc vat
manh hai » lanh hai, minh hai, thanh hai
manh vai » manh va, manh khai, hanh vi
nam thuc » nam thuoc, am thuc, nam thu
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
hieu ve » hieu van
va viet » hoa viet, san viet, mai viet
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: thu sach ky nang x hoi. ((hieu ve) OR (hieu va)) nam thuc dan ((manh vai) or (manh hai)) va viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang x hoi. ((hieu ve) OR (hieu va)) nam thuc dan ((manh vai) OR (manh hai)) va viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang x hoi. ((hieu ve) OR (hieu va)) nam thuc dan ((manh vai) or (manh hai)) va viet".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang x hoi. ((hieu ve) OR (hieu va)) nam thuc dan ((manh vai) or (manh hai)) va viet*.