Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
sang mai » sang ma, sang tai, lang mai
tu sach » su sach, te sach, tu cach
cua tre » cua te, cua triet, dua tren
hanh va » hang va, hanh vi
va hanh » van hanh, va thanh, va danh
cac luc » cau luc, coc luc, cac nuoc
cuu tre » cau tren, cau treo
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai hoi
ky sang » ky nang, ky dang, ky tang
luc va » duc va, tuc va, loc va
ve cac » va cac, vien cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (thu sach)) ky sang mai hoi. hieu ve cac luc va hanh va ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ky sang mai hoi. hieu ve cac luc va hanh va ((cua tre) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ky sang mai hoi. hieu ve cac luc va hanh va ((cua tre) or (cuu tre))*.