Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
su triet » su viet, su tien, ve triet
hieu ve » hieu va, hieu van
hanh ki » hanh vi, hanh ky, hanh kien
y nang » ky nang, ly nang, v nang
ve bac » ve bao, ve cac, ve ban
bo van » vo van, so van, do van
o hoi » co hoi, o hoc, o hoa
o hai » co hai, so hai, o lai
ki su » ky su

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach y nang ((o hoi) or (o hai)). hieu ve bac bo van hanh ki su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y nang ((o hoi) OR (o hai)). hieu ve bac bo van hanh ki su triet.
• Adding a wildcard symbol may retrieve word variants: thu sach y nang ((o hoi) or (o hai)). hieu ve bac bo van hanh ki su triet*.