Nature:

v.229 yr.1971; v.229-231 1971 Jan-Jun; v.229-231 1971; v.229-230 1971 Jan-Apr; v.229 1971; v.229-230 no.1-17; v.230 yr.1971; v.230 1971; v.230:12 1971; v.230:13 1971; v.230:14 1971; v.230:16 1971; v.230:17 1971; v.231 yr.1971; v.231 1971; v.231-232 no.18-34; v.232 yr.1971; v.232-234 1971 Jul-Dec; v.232-234 1971; v.232 1971; v.233 yr.1971; v.233 1971; v.233-234 no.35-52; v.234 1971; v.235-237 1972 Jan-Jun; v.235-237 1972; v.235 1972; v.235-236 no.55-69; v.236 yr.1972; v.237 yr.1972; v.237 1972; v.237-238 no.70-87; v.238 yr.1972; v.238-240 1972 Jul-Dec; v.238-239 1972; v.238 1972; v.239 yr.1972; v.239 1972; v.239-240 no.88-104; v.240 yr.1972; v.240:96-104 1972; v.240-241 1972-1973; v.241-243 1973 Jan-Jun; v.241:105-113 1973; v.242 1973; v.242:114-121 1973; v.242 no.105-121; v.243 yr.1973; v.243:122-130 1973; v.243 no.122-130; v.244 yr.1973; v.244-246 1973 Jul-Dec; v.244-246 1973; v.244 1973; v.244 no.131-139; v.245 1973; v.245:140-148 1973; v.245 no.140-148; v.246 1973; v.246 no.149-155