Perhaps you should try some spelling variations:
canh tac » canh tay, canh giac, cong tac
van hanh » van thanh, ban hanh, van anh
cau tren » cu tren, dau tren, ca tren
te sach » toc sach
sach ky » sac ky, sach y, sach ty
ky canh » ky anh, ky cach, ky danh
tac hoi » tao hoi, tay hoi, tac hai
luc van » luoc van, luu van, duc van
hanh di » hanh vi, hanh de, hang di
va cam » va cham, va cac, va cai
va cao » va cac, va co, va dao
di cau » da cau, diem cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky canh tac hoi. lieu ((va cam) or (va cao)) luc van hanh di cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky canh tac hoi. lieu ((va cam) OR (va cao)) luc van hanh di cau tren.
• Adding a wildcard symbol may retrieve word variants: te sach ky canh tac hoi. lieu ((va cam) or (va cao)) luc van hanh di cau tren*.