Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
toc sach » hoc sach, doc sach, thuoc sach
tinh de » tinh da, sinh de, tinh he
va tinh » may tinh
cac dac » cac dan, cac dai, cac bac
hieu va » lieu va
xang o » lang o, tang o, dang o
dac va » duc va, day va, dat va
y xang » ty xang
o hoc » co hoc, mo hoc, so hoc
de su » den su, ve su, de tu

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) or (toc sach)) y xang o hoc. ((hieu va) or (hieu qua)) cac dac va tinh de su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) y xang o hoc. ((hieu va) OR (hieu qua)) cac dac va tinh de su triet.
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) y xang o hoc. ((hieu va) or (hieu qua)) cac dac va tinh de su triet*.