Henry Qian writes:

[...]

>What tools do I need in order to read them?

They're troff-source for the papers, troff is a document processing
language, originally producing output for a certain phototypesetter
(A predecessor to troff was actually one of the first applications
Unix was used for.)
A version called nroff is also available for producing a text rendition
for terminals.

NetBSD ships with Gnu groff, which can also produce ASCII (used
for manpages) and Postscript (and TeX DVI and HTML in newer versions).
Most troff documents use macros, the papers in /usr/share/doc usually
use the ms or me macros.  Depending on the document, you might need
to preprocess the stuff with eqn or tbl (equation or table preprocessors).

To produce a postscript document from source which uses the ms macros,
you might for example say:
	groff -Tps -ms < file.ms > file.ps
or
	eqn < file.ps | tbl | groff -Tps -ms > file.ps
to preprocess the file with the eqn and tbl preprocessors.

To produce a text rendition of the document, you can use
	nroff -ms <file.ms > file.txt
(nroff should be equivalent to groff -Tascii, iirc.)

--mkb