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For the most part you probably do not need a manual for an ordinary conventional cathode-ray oscilloscope. Usually a 5" round face, masked to a rectangular area.
Basically this is a three axis device, X, Y, Z. Where X is horizontal and most often used as a linear time base; Y is vertical (maybe more than one channel) and is the usual signal channel; and Z is the beam intensity. Z in an oscilloscope is not often used other than as a fixed level, or in some cases to identify a certain time region.
When X is used as a time base, the usual case, it is usually generated internally by a saw tooth generator with adjustable rates and sync capability. This might range from 5 sec/cm to 0.1 microsec/cm. Sync may be selectable internally from one of the Y channels, or internally from line frequency, or external. In some scopes (Tektronix) since the 40's there has existed the ability to select slope (neg or positive ), and amplitude. Also AC or DC coupling.
Both X and Y external usually have DC or AC coupling available. Range switches are usually in a 1, 2, 5 sequence.
There will be an intensity and a focus control.
If the X axis ( horizontal ) is switched to external, then you can do an X Y plot of one voltage vs another. In this mode if you plot one sine wave vs another you can genetrate Lissajous figures. For limited discussion see p 467 of "Basic Electrical Measurements" by Melville B. Stout, University of Michigan, 1950, Prentice-Hall. This is a good book for a study of bridge circuits. Two sine waves of the same frequency and phase produce a straight line at an angle. With one at 90 deg phase shift you get an ellipse. If deflection sensitivity is the same in both X and Y, then 90 deg produces a circle. Other phase angles can be estimated from the angle of the ellipse. Integral related frequencies produce interesting curves.
Keep the intensity at a minimum for your purpose to avoid burning the screen.
Experiment and find out what you can do.