Perhaps you should try some spelling variations:
trinh co » trinh do, trinh cong, trinh hoa
trien do » trien dot, tien do, trien du
gia cong » cua cong, va cong
toc sach » hoc sach, doc sach, thuoc sach
tu sach » thu sach, su sach, te sach
tren do » tren doi, tren co, tren go
tinh co » tinh cao, tinh cho, tich co

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 ((tren do) or (trien do)) gia cong ) or ( toc sach ((tinh co) OR (trinh co)) gia cong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach ((tren do) OR (trien do)) gia cong ) OR ( toc sach ((tinh co) OR (trinh co)) gia cong )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu sach ((tren do) or (trien do)) gia cong ) or ( toc sach ((tinh co) OR (trinh co)) gia cong ))".
• Adding a wildcard symbol may retrieve word variants: (( tu sach ((tren do) or (trien do)) gia cong ) or ( toc sach ((tinh co) OR (trinh co)) gia cong ))*.