@Tien-ChengHuang Maybe yu can ask people in chat...? (Like with other math-related question.) Of course you§re not guaranteed that somebody answers. (As is always the case, if you ask something in chat or on the main site.)
Some tips on searching can be found on meta - have a look at question tagged search.
You can choose to sort those question by votes or use the frequent tab, to get the more relevant posts to the top.
In those post on meta you will also find some links to related question on the main site.
I am not sure to which extent such practice should be encouraged, but occasionally people simply ask on meta when they are looking for a specific question. Like here: meta.math.stackexchange.com/questions/21776/…