Problems while linking Fortran program (-> undefined reference to...)

Hello,

we are a group of students (mechanical engineering) who are trying to port UNIX-software to a PC Linux system during a study project. The first goals were achieved: compiling the Fortran code and creating object files. However, we encounter errors during the linking process.

This is the command we used (g77 is the Fortran77-compiler provided in gcc):

g77 -o taurus *.o ../diglib/diglib.a -lX11

And this is what the bash answered us:

exita.o: In function `exita_':
exita.f:(.text+0x23): undefined reference to `ieee_handler__'
getply.o: In function `getply_':
getply.f:(.text+0x6c): undefined reference to `rshift_'
getply.f:(.text+0xa9): undefined reference to `rshift_'
getply.f:(.text+0xe0): undefined reference to `rshift_'
getply.f:(.text+0x118): undefined reference to `rshift_'
getply.f:(.text+0x157): undefined reference to `rshift_'
getply.f:(.text+0x20b): undefined reference to `iabs_'
getply.f:(.text+0x490): undefined reference to `rshift_'
getply.f:(.text+0x4de): undefined reference to `rshift_'
getply.f:(.text+0x52c): undefined reference to `rshift_'
gettvm.o: In function `gettvm_':
gettvm.f:(.text+0xc0): undefined reference to `min0_'
ioset.o: In function `ioset_':
ioset.f:(.text+0x33): undefined reference to `gdx11_set_extend__'
pictur.o: In function `pictur_':
pictur.f:(.text+0x4957): undefined reference to `getinfo_'
pictur.f:(.text+0x499a): undefined reference to `getinfo_'
savply.o: In function `savply_':
savply.f:(.text+0x8b): undefined reference to `min_'
savply.f:(.text+0xb0): undefined reference to `max_'
savply.f:(.text+0xd5): undefined reference to `min_'
savply.f:(.text+0xfa): undefined reference to `max_'
savply.f:(.text+0x11f): undefined reference to `min_'
savply.f:(.text+0x1bc): undefined reference to `abs_'
savply.f:(.text+0x1d4): undefined reference to `max_'
savply.f:(.text+0x1eb): undefined reference to `min_'
savply.f:(.text+0x208): undefined reference to `min_'
savply.f:(.text+0x221): undefined reference to `max_'
savply.f:(.text+0x23a): undefined reference to `min_'
savply.f:(.text+0x253): undefined reference to `max_'
savply.f:(.text+0x2b8): undefined reference to `lshift_'
savply.f:(.text+0x2cd): undefined reference to `lshift_'
savply.f:(.text+0x2ee): undefined reference to `lshift_'
savply.f:(.text+0x345): undefined reference to `lshift_'
savply.f:(.text+0x3d4): undefined reference to `lshift_'
savply.o:savply.f:(.text+0x3e9): more undefined references to `lshift_' follow
taurus.o: In function `MAIN__':
taurus.f:(.text+0xc): undefined reference to `abrupt_underflow__'
taurus.f:(.text+0x26): undefined reference to `ieee_handler__'
taurus.f:(.text+0x232): undefined reference to `ieee_handler__'
collect2: ld returned 1 exit status

We presume that we need further libraries in order to successfully link the program, unfortunately we are no programmers and thus do not know which libraries could solve the problems.
Any help would be very much appreciated.

Kind regards,
Dynamo