The rule of thirds | DigicamGuides.com: "Rules Are Meant to be Broken
Calling the rule of thirds a 'rule' makes it sound like all photographs that don't follow this approach are pretty much awful and boring. Not the case.
There are thousands of examples the world over of amazing eye-catching photos that do not follow the rule of thirds. Many don't seem to follow any 'rule' at all."
Golden ratio - Wikipedia, the free encyclopedia: "In mathematics and the arts, two quantities are in the golden ratio if the ratio of the sum of the quantities to the larger one equals the ratio of the larger one to the smaller. The golden ratio is an irrational mathematical constant, approximately 1.6180339887. Other names frequently used for the golden ratio are the golden section (Latin: sectio aurea) and golden mean"
golden section - Google Search: "What is the Golden Section, Golden Mean, Golden Spiral, Golden Ratio. How to use them in the photography. Rules of Composition."
Golden Section and Rule of Thirds (Golden Mean, Golden Ratio, Golden Spiral, Golden Proportion, Golden Triangles).: "Golden Triangles
Another rule is the 'Golden Triangles'. It's more convenient for photos with diagonal lines. There are three triangles with corresponding shapes. Just roughly place three subjects with approximate equal sizes in these triangles and this rule would be kept."