in research papers....?

Question

...sometimes theres (1) or (2) after the sentence and it is linked to the bibliography, what are they called? and how do you use them?

Answer 1

they are called citations
there are many different types of citations and using citations is covered in many "how to do a research paper" books and references

bud's easy research paper book is a very good one

Answer 2

footnotes and endnotes

you use them to cite where you got your information from so that you won't be accused of plagiarism. Check out this link for more info: www.aresearchguide.com/7footnot.html