Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
cua viet » ca viet, hoa viet, cua dieu
sach tu » sach thu, cach tu, sach ty
tang ma » mang may, tang van
hieu va » lieu va, hieu qua
va cham » va chat, va tham
dan vai » dan va, dan tai, dan vat
soc va » hoc va, loc va, doc va
va dan » ca dan, va dao, va dau

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 tu ((tang ma) or (nang x)) hoi. hieu va cham soc va dan vai ((cua viet) OR (cua vat))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach tu ((tang ma) OR (nang x)) hoi. hieu va cham soc va dan vai ((cua viet) OR (cua vat)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach tu ((tang ma) or (nang x)) hoi. hieu va cham soc va dan vai ((cua viet) OR (cua vat))".
• Adding a wildcard symbol may retrieve word variants: thu sach tu ((tang ma) or (nang x)) hoi. hieu va cham soc va dan vai ((cua viet) OR (cua vat))*.