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 - frequncy domain correlation
     - [cc_freq](src/cc_freq.c): do cross-correlation using [FFTW](http://www.fftw.org/)
-    - [correlatec](src/correlatec.c): call SAC's `crscor` in SAC's [libsac](http://ds.iris.edu/files/sac-manual/manual/saclib.html) ([Chinese notes](https://seisman.github.io/SAC_Docs_zh/libs/libsac/#crscor)) to do cross-correlation
+    - [correlatec](src/correlatec.c): call `crscor` in SAC's [libsac](http://ds.iris.edu/files/sac-manual/manual/saclib.html) ([Chinese notes](https://seisman.github.io/SAC_Docs_zh/libs/libsac/#crscor)) to do cross-correlation
     - [sac_wfcc](sac_wfcc/): this is [Lupei Zhu's code](http://geophysics.eas.gatech.edu/people/zpeng/Teaching/SAC_Tutorial/#part3_1)
     - PCC2: this is [Martin Schimmel's code](http://diapiro.ictja.csic.es/gt/mschi/SCIENCE/pcc2_method.py)
     - ObsPy: [corss_correlation](https://docs.obspy.org/packages/autogen/obspy.signal.cross_correlation.html#module-obspy.signal.cross_correlation)