Perhaps you should try some spelling variations:
hieu hieu » hien hieu, hieu hien, thien hieu
thu sach » tu sach, thuat sach, thuoc sach
hieu cac » hieu luc, hieu va, hieu van
cua viet » ca viet, hoa viet, cua vat
nang mai » nang ma, nang tai, lang mai
mai hoi » mai khoi, dai hoi, lai hoi
ty nang » ky nang, ty xang, ty hang
sach ty » sach y, sach tu, sach thu
hanh di » hanh vi, hang di, danh di
hanh de » hanh ve, hanh kem
loc va » hoc va, luc va

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