Perhaps you should try some spelling variations:
tham hoc » tham hoa, than hoc, thao hoc
thai hoc » dai hoc, bai hoc, hoi hoc
te sach » toc sach
tang xa » trang xa, tang ma, lang xa
va xanh » va danh, va hanh, va anh
doi cua » dai cua, hoi cua
y tang » ky tang, 6 tang, 7 tang
do cua » co cua, de cua, dong cua

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 y tang xa hoi. lieu va ((tham hoc) OR (thai hoc)) va xanh ((do cua) or (doi cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach y tang xa hoi. lieu va ((tham hoc) OR (thai hoc)) va xanh ((do cua) OR (doi cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach y tang xa hoi. lieu va ((tham hoc) OR (thai hoc)) va xanh ((do cua) or (doi cua)) tre".
• Adding a wildcard symbol may retrieve word variants: te sach y tang xa hoi. lieu va ((tham hoc) OR (thai hoc)) va xanh ((do cua) or (doi cua)) tre*.