Perhaps you should try some spelling variations:
hieu hieu » hien hieu, hieu hien, thien hieu
thu sach » tu sach, thuat sach, thuoc sach
cua viet » hoa viet, cua vat, cua dieu
hieu cac » hieu luc, hieu va, hieu van
sach ty » sach y, sach tu, sach thu
hanh di » hanh vi, hanh de, hang di
ca viet » va viet, co viet, hoa viet
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
loc va » hoc va, luc va
ma hoi » mai hoi, xa hoi, ma hoa

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 ty nang ma hoi. hieu hieu cac ((duc va) or (loc va)) hanh di ((cua viet) OR (ca viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ty nang ma hoi. hieu hieu cac ((duc va) OR (loc va)) hanh di ((cua viet) OR (ca viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ty nang ma hoi. hieu hieu cac ((duc va) or (loc va)) hanh di ((cua viet) OR (ca viet))".
• Adding a wildcard symbol may retrieve word variants: thu sach ty nang ma hoi. hieu hieu cac ((duc va) or (loc va)) hanh di ((cua viet) OR (ca viet))*.