Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
kinh hai » tinh hai, minh hai, dinh hai
kinh vai » kinh va, kinh van, sinh vat
nam thuc » nam thuoc, am thuc, nam thu
sach ky » sac ky, sach y, sach ty
ca viet » va viet, hoa viet, san viet
thuc va » thuc vat, thuc dan, thuc day
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
co viet » so viet, o viet, hoc viet
va nam » van nam, ha nam, va nay

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky nang xa hoi. hieu va nam thuc va ((kinh vai) or (kinh hai)) ((ca viet) OR (co viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang xa hoi. hieu va nam thuc va ((kinh vai) OR (kinh hai)) ((ca viet) OR (co viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky nang xa hoi. hieu va nam thuc va ((kinh vai) or (kinh hai)) ((ca viet) OR (co viet))".
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang xa hoi. hieu va nam thuc va ((kinh vai) or (kinh hai)) ((ca viet) OR (co viet))*.