The kinds of application for job. Applicant can submit his application for job based on 3 types.
1. Answering Advertisements
2. Seeking Unadvertised Position (Self Opinion)
3. References and Recommendations

There are the example each type.
1. Answering Advertisements
Dear Sirs:

I am applying for the position as bookkeeper which you have advertised in the Herald Courier. I have enclosed a copy of my resume.

Your truly,

2. Seeking Unadvertised Position (Self Opinion)

Dear Mr. Hammond:

This is for your files. I know there is no position in your office at present, but I should like to be considered when there is one.

I am enclosing a list of my jobs and references.

Your sincerely,

3. References and Recommendations

Dear Mr. Rogers:

The bearer of this letter, Miss Helen Jones, has worked for me for six years. She is one of the most able secretaries and bookkeepers we have had. I think you would find her a very valuable addition to your organization.

Yours sincerely,

Ref:
A.E. Klien.—. The New World Secretarial Handbook. Collins World
Soehary . 1996. Surat Menyurat Bahaa Inggris II