Acknowledgements are usually given between the body of the paper and the references. Financial support or provision of supplies used in the study should be acknowledged first. However, if you have already mentioned a gift of supplies in the Materials and Methods section, do not repeat it here. Then you may acknowledge other forms of assistance (eg for technical assistance, discussion of the manuscript, preparation of the paper or statistical review). If the study was done by a large group of people, the names of all of the participants may be given in this section.

example:

"We thank all the cancer registries that contributed to the databases used in this study, and Georgia Harrison for statistical advice. We also acknowledge the technical assistance provided by Ricardo Strum."

"This work was supported in part by grants-in-aid from the Ministry of Science, Education, Sports and Culture and from the Science and Technology Agency, Japan"