Perhaps you should try some spelling variations:
may thoi » gay thoi, may thi, tay thoi
van hanh » van thanh, ban hanh, van anh
hanh dao » lanh dao, thanh dat, thanh dam
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
ky mang » ky nang, ke mang, ky dang
may hoi » tay hoi, mai hoi, may hmi
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
tuc van » thuc van, truc van, tuc va
su viet » so viet
dao su » dao suu, dan su, cao su

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 mang ((may hoi) or (may thoi)). hieu va cac tuc van hanh dao su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky mang ((may hoi) OR (may thoi)). hieu va cac tuc van hanh dao su viet.
• Adding a wildcard symbol may retrieve word variants: tu sach ky mang ((may hoi) or (may thoi)). hieu va cac tuc van hanh dao su viet*.