Perhaps you should try some spelling variations:
viet tech » viet sach
hieu viet » sieu viet, hieu viec, lieu viet
tech nuoc » dich nuoc, sach nuoc
nang mai » nang ma, nang tai, lang mai
su sach » so sach, vu sach
mai hoi » mai khoi, dai hoi, lai hoi
va xanh » va danh, va hanh, va anh
y nang » ky nang, ly nang, v nang
di cua » doi cua, de cua, do cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach y nang mai hoi. hieu viet tech nuoc va xanh ((di cua) OR (dai cua)) triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y nang mai hoi. hieu viet tech nuoc va xanh ((di cua) OR (dai cua)) triet".
• Adding a wildcard symbol may retrieve word variants: su sach y nang mai hoi. hieu viet tech nuoc va xanh ((di cua) OR (dai cua)) triet*.