Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
va triet » va trien, ve triet, cua triet
tinh vai » tinh va, tinh hai, tinh bai
nam thuc » nam thuoc, am thuc, nam thu
va tinh » may tinh
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
va nam » van nam, ha nam, va nay
ma hoi » mai hoi, xa hoi, ma hoa
y nang » ky nang, ly nang, v nang
thiet » thieu

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

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