1. DM Anderson, and MM Kothmann .1982 .A two-step sampling technique for crop of herbaceous vegetation .J Range Manage,35:675 -77 .
2. RF Daubenmire .1959 .A canopy coverage method of vegetational analysis .Northwest Sci,35:43 -64 .
3. S. De Becker, and D. Mahler .1986 .Photographing quadrats to measure percent vegetation cover .Nat Area J,6:67 -69 .
4. TJ Hatton, NE West, and PS Johnson .1986 .Relationships of the error associated with ocular estimation and actual total cover .J Range Manage,39:91 -92 .
5. KF Higgins, LM Kirsch, and IJ Ball .1969 .A cable-chain device for locating duck nests .J Wildlife Manage,33:1009 -11 .