Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
dinh ve » dinh ket, dinh van
va dinh » van dinh, va kinh, va tinh
nang ma » tang ma, sang ma, nang cao
su viet » so viet
ma hoi » mai hoi, xa hoi, ma hoa
dam tu » nam tu, cam tu, dam thuc
tam tu » nam tu, cam tu, tam thuc
ve su » va su

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) or (hoc sach)) ky nang ma hoi. hieu qua ((dam tu) OR (tam tu)) va dinh ve su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) ky nang ma hoi. hieu qua ((dam tu) OR (tam tu)) va dinh ve su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (hoc sach)) ky nang ma hoi. hieu qua ((dam tu) OR (tam tu)) va dinh ve su viet".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (hoc sach)) ky nang ma hoi. hieu qua ((dam tu) OR (tam tu)) va dinh ve su viet*.