Perhaps you should try some spelling variations:
van cham » van chat, van tham, va cham
cham luc » cham soc, nhan luc, cham cuu
hanh tai » thanh tai, hang tai, han tai
hai khoi » mai khoi, tai khoi, thai khoa
hieu van » hieu va, thien van, lieu va
cuu tre » cua tre, cau tren, cau treo
va hanh » van hanh, va thanh, va danh
tu sach » thu sach, su sach, te sach
ky dang » ky nang, ky danh
ky lang » ky nang, ky tang, tay lang
cu tren » tu tren, dua tren
luc va » duc va, tuc va, loc va

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 ((ky lang) OR (ky dang)) hai khoi. hieu van cham luc va hanh tai ((cuu tre) or (cu tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky lang) OR (ky dang)) hai khoi. hieu van cham luc va hanh tai ((cuu tre) OR (cu tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky lang) OR (ky dang)) hai khoi. hieu van cham luc va hanh tai ((cuu tre) or (cu tren))".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky lang) OR (ky dang)) hai khoi. hieu van cham luc va hanh tai ((cuu tre) or (cu tren))*.