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

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