The reference BLAS sources are part of the netlib LAPACK distribution.
This goes way back in R and were moved to this directory in 2006.  The
netlib sources have been commented and re-indented since.

Routine ZHER2K was patched in 2013 in c62981 (the netlib sources have
not been).

File blas.f contains
dasum daxpy dcopy ddot dgbmv dgemm dgemv dger dnrm2 drot drotg drotm
drotmg dsbmv dscal dsdot dspmv dspr2 dspr dswap dsymm dsymv dsyr2
dsyr2k dsyr dsyrk dtbmv dtbsv dtpmv dtpsv dtrmm dtrmv dtrsm dtrsv
idamax lsame

In LAPACK 3.10.0 dnrm2 and drotg were re-written in F90 using min/maxexponent.

File cmplxblas.f contains
dcabs1 dzasum dznrm2 izamax zaxpy zcopy zdotc zdotu zdrot zdscal zgbmv
zgemm zgemv zgerc zgeru zhbmv zhemm zhemv zher2 zher2k zher zherk
zhpmv zhpr2 zhpr zrotg zscal zswap zsymm zsyr2k zsyrk ztbmv ztbsv
ztpmv ztpsv ztrmm ztrmv ztrsm ztrsv

Ditto znrm2 and zrotg