Perhaps you should try some spelling variations:
cam truc » cau truc, nam truc, lam truoc
sach van » sach han, sach va, bach van
van nang » van quang, van ban, van dong
van hanh » van thanh, ban hanh, van anh
truc van » truc va, thuc van, truc ban
cua tre » cua te, cua triet, dua tren
hanh de » hanh ve, hanh kem
vu sach » vu bach, su sach, vu khach
hieu ve » hieu va, hieu van
cuu tre » cau tren, cau treo
ve cam » ve cham, ve cac, va cam
x hoi » xa hoi, o hoi, 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: vu sach van nang ((x hoi) OR (x ho)). hieu ve cam truc van hanh de ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach van nang ((x hoi) OR (x ho)). hieu ve cam truc van hanh de ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach van nang ((x hoi) OR (x ho)). hieu ve cam truc van hanh de ((cua tre) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: vu sach van nang ((x hoi) OR (x ho)). hieu ve cam truc van hanh de ((cua tre) or (cuu tre))*.