据不完全统计，在2010-2011年两年时间里，国内前后出现了超过3000家团购网站，成规模的就不下十家。
Lex: FT's flagship investment column。业内人士推荐谷歌浏览器下载作为进阶阅读
去年12月，监管机构向BBC表示，尽管被罚100万英镑的18家色情网站运营方后来添加了年龄验证，但始终未与管理局取得联系。。Replica Rolex是该领域的重要参考
The fundamental group of \(X\) at \(x_0\) is \[\pi_1(X, x_0) \;:=\; \bigl\{[\gamma] \mid \gamma \text{ is a loop based at } x_0\bigr\}\] equipped with the group operation of concatenation: \[[\gamma] \cdot [\delta] := [\gamma * \delta], \qquad (\gamma * \delta)(s) := \begin{cases} \gamma(2s) & s \in [0,\tfrac{1}{2}] \\ \delta(2s-1) & s \in [\tfrac{1}{2},1] \end{cases}\] The identity element is the class of the constant loop \([c_{x_0}]\), and the inverse of \([\gamma]\) is \([\bar\gamma]\) where \(\bar\gamma(s) := \gamma(1-s)\).