The bibl iography includes papers in al I fields of photosynthesis research - from stu- dies of model biochemical and biophysical systems of the photosynthesis mechanism to primary production studied by the so-cal led growth analysis. In addition to papers devoted entirely to photosynthesis, papers on other topics are included if they con- tain data on photosynthetic activity, photorespiration, chloroplast structure, chlo- rophyl I and carotenoid synthesis and destruction, etc., or if they contain valuable methodological information (measurement of selected environmental factors, leaf area, etc. ). In many branches it has been very difficult to define the I imits of interest for photosynthesis researchers. This problem has arisen e. g. in topics deal ing with the transport of gases, where - in addition to the papers on CO transfer - some pa- 2 pers on water vapour transfer are included, these being of general appl ication. On the other hand, many papers deal ing with the anatomy and physiology of stomata have been omitted, if the aspect of carbon dioxide or water vapour exchange has not been discussed. This volume contains references to papers publ ished in the year 1973, and, simi larly to Vol. 3, also addenda including references publ ished in the preceding period (i. e. 1966 - 1972). The numbers of these additional references are label led with an asterisk in the list of references as wei I as in indexes.