There is no simple method to describe how the search is to be approached. A study may contain many techniques and procedures and each of them capable of inducing pain or distress would have to be considered in the alternatives search. A study that involves implanting a jugular catheter to measure blood oxygenation and inducing a specific pulmonary infection in a rabbit would require two different approaches to the search. To string together the keywords rabbit, catheter, and pulmonary infection would not lead to useful results, if indeed any results are obtained at all. The first step would be to examine the nature of the measurement and to determine if a transcutaneous method is possible. In the second instance, it would be more useful to review the literature on lung infection without reference to "rabbit". To limit to a specific species is to ignore the fact that the infection may not be specific to a particular species and alternatives may be adapted from studies of other animals. While in some cases the techniques are unique to the field of the research and the search should proceed in the scientific literature of that discipline, in many cases the methods are sufficiently general to permit searching across a number of areas of interest.