Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
nang mai » nang ma, nang tai, lang mai
hieu van » hieu va, thien van, lieu va
chau phu » chau phi, chau au, chau tho
sach ky » sac ky, sach y, sach ty
danh vi » dinh vi, danh di, danh va
ca tren » cau tren, cu tren, la tren
cau luc » cau truc, cau phuc
mai hoi » mai khoi, dai hoi, lai hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ky nang mai hoi. hieu van ((cau luc) or (chau phu)) va ((danh vi) OR (hanh vi)) ca tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ky nang mai hoi. hieu van ((cau luc) OR (chau phu)) va ((danh vi) OR (hanh vi)) ca tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ky nang mai hoi. hieu van ((cau luc) or (chau phu)) va ((danh vi) OR (hanh vi)) ca tren".
• Adding a wildcard symbol may retrieve word variants: hoc sach ky nang mai hoi. hieu van ((cau luc) or (chau phu)) va ((danh vi) OR (hanh vi)) ca tren*.