revise Qin's text

Author: bqminh

doc/Advanced-Tutorial.md

@@ -528,11 +528,14 @@ Trimming alignment sites by likelihood
 <div class="hline"></div>
 
 Phylogenetic inference can be highly sensitive to fast-evolving, saturated or
-erroneous sites in a sequence alignment. To address this issue,  IQ-TREE
-implements the **trimmed log-likelihood** method - a robust and dynamic approach
-that improves tree inference by selectively down-weighting problematic sites. 
-
-This method works by dynamically excluding a user-defined proportion of sites
+erroneous sites in a sequence alignment. Many studies used Gblocks 
+([Castresana, 2000]) or trimAl ([Capella-Gutiérrez et al., 2009])
+to trim alignment sites prior to phylogenetic reconstruction.
+Here, we present an alternative approach called  **trimmed log-likelihood**, a 
+robust phylogenetics method, that automatically detects and trims such sites 
+during tree search directly.
+
+The trimed log-likelihood method works by dynamically excluding a user-defined proportion of sites
 with the lowest log-likelihood values during the tree search. As the search
 progresses,  the likelihood of each site is recalculated at each step using
 current tree and model parameters.  This ensures that site removal is always
@@ -577,6 +580,8 @@ Where to go from here?
 
 See [Command Reference](Command-Reference) for a complete list of all options available in IQ-TREE.
 
+[Capella-Gutiérrez et al., 2009]: https://doi.org/10.1093/bioinformatics/btp348
+[Castresana, 2000]: https://doi.org/10.1093/oxfordjournals.molbev.a026334
 [Gadagkar et al., 2005]: https://doi.org/10.1002/jez.b.21026
 [Kishino et al., 1990]: https://doi.org/10.1007/BF02109483
 [Kishino and Hasegawa, 1989]: https://doi.org/10.1007/BF02100115