Perhaps you should try some spelling variations:
van cham » van chat, van tham, va cham
cham duc » pham duc, cham soc, pham duy
van hanh » van thanh, ban hanh, van anh
hieu van » hieu va, thien van, lieu va
loai ca » loai cay, loai cua, loai va
duc van » duc va, duc tan, duc manh
tu sach » thu sach, su sach, te sach
ty nang » ky nang, ty xang, ty hang
sach ty » sach y, sach tu, sach thu
lai ca » lai cua, lai cam, bai ca
x hoi » o hoi, x ho, 5 hoi

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 ty nang ((x hoi) or (xa hoi)). hieu van cham duc van hanh ((lai ca) OR (loai ca)) viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang ((x hoi) OR (xa hoi)). hieu van cham duc van hanh ((lai ca) OR (loai ca)) viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang ((x hoi) or (xa hoi)). hieu van cham duc van hanh ((lai ca) OR (loai ca)) viet".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang ((x hoi) or (xa hoi)). hieu van cham duc van hanh ((lai ca) OR (loai ca)) viet*.