fix wrong facts in intro

ref.bib

@@ -73,6 +73,33 @@
   year    = {1999},
   pages   = {787--832}
 }
+@INPROCEEDINGS{leighton_multicommodity_1988,
+  author={Leighton, T. and Rao, S.},
+  booktitle={[Proceedings 1988] 29th Annual Symposium on Foundations of Computer Science}, 
+  title={An approximate max-flow min-cut theorem for uniform multicommodity flow problems with applications to approximation algorithms}, 
+  year={1988},
+  volume={},
+  number={},
+  pages={422-431},
+  keywords={Application software;Approximation algorithms;Laboratories;Computer science;Particle separators;Linear programming;Contracts;Mathematics;Constraint theory;Bifurcation},
+  doi={10.1109/SFCS.1988.21958}}
+
+@article{garg_approximate_1996,
+	title = {Approximate {Max}-{Flow} {Min}-({Multi}){Cut} {Theorems} and {Their} {Applications}},
+	volume = {25},
+	issn = {0097-5397},
+	url = {https://epubs.siam.org/doi/10.1137/S0097539793243016},
+	doi = {10.1137/S0097539793243016},
+	number = {2},
+	urldate = {2025-05-20},
+	journal = {SIAM Journal on Computing},
+	author = {Garg, Naveen and Vazirani, Vijay V. and Yannakakis, Mihalis},
+	month = apr,
+	year = {1996},
+	note = {Publisher: Society for Industrial and Applied Mathematics},
+	pages = {235--251},
+}
+
 
 @inproceedings{lee_genus_2010,
   title      = {Genus and the geometry of the cut graph: [extended abstract]},
@@ -289,4 +316,5 @@ series = {SODA '95}
 	month = jan,
 	year = {2013},
 	pages = {295--305},
-}
+}
+@book{Williamson_Shmoys_2011, place={Cambridge}, title={The Design of Approximation Algorithms}, publisher={Cambridge University Press}, author={Williamson, David P. and Shmoys, David B.}, year={2011}}